The Ex and I had an open relationship during our marriage and before. She would visit me at the bar I worked at, adding some cash to our structured pay as I was an E-3 in the late 70's. She would come in and sometimes play hotwife pickup or zero in on some unassuming individual. She would look for a single guy and chat him up, possibly take him out to the car for a romp in the backseat or a blowjob depending on her mood. I was working one night when one of the newer guys I was talking to said there was going to be a party in the barracks and to stop by if I could. The Ex had said she was going to be out with her friends so I said I would drop by. It was a slow night so we closed early, I decided to head to the barracks. When I got there the dayroom was set up with a keg and some snacks, someone had brought some porn and there were about 15 guys standing around talking. One of the guys said there was entertainment in one of the rooms, but there were about 20 guys in there right now. I had a drink or two and noticed a few guys coming out of one of the rooms, some clapping and cheering going on, so I decided to check it out. As i entered the room, there was an open door that led to a shared bathroom, all the noise coming from the other room, this room had clothes all over the place.
As I entered the room, which was darkened, I see a few guys standing and 3 women on mattresses, placed in the room. At first I saw a friend of mines wife on her back, Cindy had a cock in her mouth and one in her pussy, next to her was Amanda, another guy's wife I knew from some parties taking one doggie and next to her was the Ex , a guy with a good size cock laying on his back her impaled and grinding it, another guy in her Ass taking it deep, and two more up by her head alternating between both giving them head. All 3 were moaning like whores in heat (which they were) as they were getting pounded. As this was the 70's and STD's were not a big thing most were bareback. The guy in her ass blew his load and pulled out, she stops blowing and shouts "next, Fill my ass". Another guy steps up and proceeds to stick his cock in as she let's out a moan. I decide I may as well join in the fun, stepping back in the first room and removing my clothes. As I step back in the guy under her has blown his load, he pulls out they all shift positions, her paying attention to their cocks and not seeing me walk in.
Another guy she was giving head to moves to her ass, so I move up and stick my cock in her face, she looks up, sees me and has a panicked look. I tell her relax, as she sucks on the other guy's cock. I then move over to Amanda, she looks up and has pretty much the same look, Cindy looking over and eyes get big. I start pumping my cock in Amandas mouth as another guy is doing her doggie. Because of the situation I only lasted a minute or two, her swallowing my load. I left at this point and got dressed and went home. About an hour goes by and in walks the Ex. She starts to panic and I tell her to relax, she tells me one of her regulars set this up and asked for friends. While we were there this became a Bimonthly thing, it was funny no one ever associated the Ex with me. Later found out this was the biggest gangbang she was in, normally about 10 guys amongst the 3 and alot of girl/girl action at most.