Wife's Fun on the Side

My wife Teresa and I have been married for 21 years. We’re in a good place in life — good jobs, two wonderful children, and a reasonably active sex life. At 44 years old, we’re both in good shape; Teresa has nearly-black medium-length hair, brown eyes, and the most sensuous lips a woman can have; a little exercise has kept her slim body in good tone, and her medium-sized boobs are still firm.
We have in-laws that live fairly close by — my wife’s sister and brother-in-law (Annie and Mike) live about two hours away, and our children are very fond of them. As a result, we visit quite often. This is about one of those visits.
We’d been at Annie and Mike’s for about a day and a half. We’d eaten out the night before and gone shopping for the kids that morning. Back at the house, the kids had headed for a playground down the street, and the adults were relaxing in front of the TV with some unmemorable movie on DVD. It was mid-February, and the house had a bit of a chill. My wife and Mike were on the couch with a blanket across the two of them, sharing it with my in-laws’ three lap dogs. I was on a big, cushy leather chair in a sweatshirt, while Annie was in the chair next to me, a small blanket across her legs. Annie almost always wears tight shirts without a bra while at home, showing off a set of spectacular boobs of which she is rightly proud — that they’re largely the work of her plastic surgeon really doesn’t matter. Both Mike and Annie are in excellent shape, and I’ve had many fantasies about what Annie and I might do together. As often happens, I spent as much time glancing at her boobs as I spent watching TV — the chill was doing a wonderful job of keeping her nipples perky. The sun was shining through a huge den window, and we were all pretty relaxed.

About a half-hour into the movie, I started noticing something odd on the couch. Normally, the dogs move around a lot — it’s an occasional distraction that I usually ignore, but this time I noticed some movement under the blanket that had nothing to do with sleeping poodles. Both of Mike’s hands were under the blanket, and one looked like it might be on Teresa’s leg. While this got my attention up, I tried to act like I was still watching TV. The fact was, nobody was paying me any attention: Annie was starting to doze in her chair, and Teresa and Mike were seemingly intent on the movie.
As I watched, I realized his hand wasn’t just on her leg, but slowly rubbing the inside of her thigh, very near her crotch. Despite my rising anxiety, I was also very excited. I’ve had my share of fantasies of one (or both) of us fucking someone else, and my cock was starting to react to what I was watching. I knew there couldn’t be much going on — Teresa was wearing long sweatpants, and there was just no way for his hand to get to anything interesting without being very obvious.
After about ten or fifteen minutes of this (honestly, it’s hard to tell), Teresa slipped her right hand under the blanket and slowly moved it over to Mike’s leg. This got me more worried, as Mike was wearing very baggy shorts, with easy access to his cock. All sorts of thought were running through my mind, and a feeling of nausea was competing with my (now rock-hard) cock. While it was hard to be certain about what was happening, Teresa’s hand started about halfway down his thigh and moved up to his crotch, and I was pretty sure she’d pushed the shorts up and out of the way to do it. Mike’s other hand, which I’d ignored until now, moved away from his crotch to make room for hers. For a while they didn’t move, but the look on Mike’s face told me that she had a hold on his dick… and he was enjoying it.
After a couple of minutes, she started a very slow up-and-down motion on his dick, and this went on for several minutes. The movement was slight — had I not noticed from the beginning, I probably would have thought nothing of it. Mike’s eyes got a little unfocussed, and there was a slight red flush around his neck. Teresa kept her eyes glued on the TV; looking back, I suspect she didn’t want to move around enough to attract attention.
At this point, Annie gave out a snore loud enough to wake herself up. Mike started up with a deer-in-headlights look, though Teresa stayed calm and looked slowly toward her sister. Teresa’s hand stopped moving, but didn’t pull away from Mike’s cock. Annie laughed, and said she better go upstairs for a nap, while I tried desperately to look nonchalant and interested in the movie (which had become far less memorable than even before).
Inside, I was going crazy. My wife was jacking off another guy, her own brother-in-law… and right in front of me! I was way too freaked out to do or say anything sensible, but I was also incredibly excited. Somehow I had the presence of mind to realize that little more would happen with me there. Mumbling something about being tired and taking a nap myself, I got up carefully (turning so they couldn’t see the hard-on under my sweats). A voice screamed in my head about what I might be letting happen, but another voice wanted something to happen.
I headed for the guest rooms at the end of the house, and closed the hall door behind me — most of the way. I left it cracked open just a bit, and peered through the narrow opening to see what would happen. I had a clear view of the couch, and anything they tried.
Mike and Teresa immediately looked at each other. My wife broke out in a mischievous smile, as if it were all a big game. Mike was smiling, too, but with that look men get in such situations. Teresa’s hand started moving, this time more forcefully, and enough to be easily seen under the blanket. For the first time I wondered what they’d done before — it all happened so calmly and carefully. Despite my worry, I slipped a hand into my sweats and grabbed my cock, which by now was hard, throbbing, and dripping pre-cum from the tip, leaving a large moist spot in my boxers.
After several minutes, Mike leaned toward Teresa and whispered something in her ear. While I was too far away to hear anything, her reaction was clear — her face got a surprised look and she shook her head. He said something else, seeming to plead: Teresa shook her head again, and I could see her lips form the word “No” to whatever he asked. Whatever was being said, her hand never stopped moving, and she looked down with some interest and satisfaction at the bulge of her hand and his cock under the blanket.
Soon after this, Mike took a hand out from under the blanket and slipped it under her shirt, again whispering into her ear. This time it evidently tickled her neck, and she smiled. Teresa’s hand stopped moving, and she sat up to look toward the stairs and the hall door. I froze, afraid that she’d see me looking out, but my end of the house and the hall were too dark for her to see anything.
With a nervous look on her face, Teresa nodded to Mike, pulled her hand from beneath the blanket, and pushed the blanket aside.
Mike got up and turned toward my wife, standing in front of her. As he turned, I could see a massive hard-on poking out under his shorts. Teresa looked at his crotch and smiled, looked up at Mike’s face, and looked down again. Reaching up to grasp his waistband at each side, she slowly pulled down his shorts; if he had on underwear, they came down at the same time — I couldn’t tell. His red, swollen cocked popped free as she pulled, bobbing inches from her face.
I was fascinated and terrified. I had thought for a time, with relief and disappointment, that she was going to stop her handjob. But now, with his dick exposed to her, my tension hit an all-time high. I realized that I’d been stroking my own cock, and started to pump harder.
From where I was I could see the head of Mike’s cock. Teresa looked once again toward the stairs and then the hall, then at Mike’s cock. Putting both hands on his ass, she opened her mouth and took him in.
Mike’s head went back in obvious ecstasy, and he put his hands on top of Teresa’s head. Teresa gives great head — with every bob I saw her face disappear from view and then reappear with her lips wrapped firmly around the head of his dick. The muscles in Mike’s butt were tensing up, and he began pumping with growing intensity. My wife was taking in his entire length, and I could see he was going to climax very soon.
Teresa’s hands moved to his hips to better control his thrusts, and Mike’s hands tightened to grab tufts of Teresa’s hair. Just as she looked up toward his face, Mike’s entire body tensed and his hips shot forward. I could hear him groan and he shot his load into my wife’s throat, and I could see her sucking and swallowing his cum as fast as she could. Though she held his dick in her mouth and kept sucking, I could see a small amount drip from the side of her face that was toward me.
My wife pulled away from Mike’s dick with a satisfied expression. She looked up at him smiling, wiping the corners of her beautiful lips with her fingers. After a half-minute or so, Mike pulled up his shorts and sat back down. At this point, I pulled my wet hand from my pants — I had cum all over my hand and the inside of my boxers, and I went to the bathroom to clean up.
This is a true story. I’ve never been so excited, or so upset, in my life. When I went to the bathroom I got sick. Several months (and several visits) later, I haven’t seen anything suspicious. I’m not sure I want to, wanting to believe that my wife is (mostly) faithful. Sex with Teresa has been more intense than ever — the memory of another man’s dick pumping into her eager mouth gets me harder than ever before, and leads to bigger orgasms than I’ve ever had.
What do I do?