I've lived with my mom and step dad as a family since I was three years old. My step dad is a very masculin guy and has a fantastic physique for a guy who's in his mid forties. He's been in the army, but finished after serving for eighteen years. Now he uses his physical training skills as a personal trainer. My mom is a very pretty woman and keeps in shape just like my step dad. She's in her late thirties and still gets admiring looks from men when were out together sometimes.

I'm nineteen year old, 5'11" tall and athletically built. I'm openly bisexual and both my mom and step dad accept my sexual and life choices. In the last year I've started dating a girl I've known for over five years. she knows I'm bisexual as I once had a brief relationship with her cousin.

Now to the actual confession.

My mom sometimes has to fly to another city as part of her job. When she does, she normally stays over a couple of days, which was the case three weeks ago. I planned on staying at my girlfriends house, as her parents were going on vacation. It was the first night my mom was away, it was late around midnight and myself and my girlfriend were horny and we really wanted to have full sex. I knew I had condoms back at home and it was only a five minutes drive away. Pulling up outside our home, I saw the motor bike and knew it to be an old army buddy of my step dads.

Not thinking anything other than getting the condoms, I opened the front door with my key and walked past the lounge door, on my way to the stairs. Looking to my right as I passed the open lounge door I had my first sight of my step dads cock.

It wasn't that hard to miss, as it was being thrust up his old army buddies ass real hard. His buddy was bent over the arm of the sofa and my step dad with his huge cock, was fucking him from behind bareback. I was ten feet away from a sexual scene I thought I would never see. My step dad is so much of a mans man, a real hard physical man. Someone who attracts womens glances and their knowing smiles. But here he was, his cock balls deep up his friends ass and by the sounds of it, both of them were having a great time.

Standing there watching them fuck was such a turn on for me and I knew right there and then, if he'd have asked me to join in, I would have. They didn't or hear me, probably because of the moaning his buddy was making, so I climbed the stairs as quietly as I could and got the packet of three condoms. Reaching the bottom of the stairs and then staring into the lounge, I saw they'd swapped positions. My step dad was sat on the couch and his buddy was happily bouncing up and down on his cock, his own cock swaying and bobbing about as he rose up and then sank right down onto my step fathers dick.

The night my girlfriend and I had was awsome. I was totally turned on and she was amazed at how much I wanted to fuck her when I got back to her house. We were still having sex when her alarm went off for her to go to college. I was so horny licking her pussy and ass until she orgasmed twice, she let me fuck her in the ass for the first time. I'd not long filled the last of the condoms up her tight little ass when her alarm started.

When I got back home the following afternoon, my step dad had just gotten in himself. He told me he'd been round to his friends house, another old army buddy. Straight away I wondered if he'd been fucking him too. I didn't say anything and wasn't going to until he spoke. He said "I'm sorry you saw what you did last night, I didn't know you would be coming back home. Anyway I am sorry you had to witness what you did. I didn't see you, but **** did as you walked out the house". I was going to say something but he added "If you're going to say something to your mom, let me speak to her first, I think she deserves that at least. If not, then maybe we should sort something out".

I didn't know what to say after that, so all I did say in a weak way was "Oh ok, I'll think about it".

It's been three weeks since I caught him fucking his buddy. I haven't told my mom, I didn't have to, he spoke to her. I thought they'd be finished, but that couldn't be futher from the truth, they're actully more loved up now than before. I was confused until my mom spoke to me two nights ago. she told me she'd always known about his extra sexual needs, just as she's known about mine. She even knew before she went away, his buddy would be staying and she accepted they'd be having sex.

Now I have a personal confession. The last couple of days I've started to see my step dad in a sexual way and I honestly think if he asked me I'd let him fuck me all ends up, in fact I know I would. It's all a bit confusing at the moment, but the one thing I do know is, I'd love to feel his large cock fucking me deep up my ass.