I'm 20 years old and three weeks ago my boyfriend of 8 months, Lachlan, left for a nine week trip to Europe to visit family. I had become pretty close with his father, Mark, in the past 8 months. The day Lachie left I was pretty upset, so his father said he would take me to the rent-a-movie store and we'd rent a couple good films to watch with him and his wife. We got back to his place and he received a call from his wife saying that she had met with a few friends from "college days" and she was going to the club to have a few drinks and she wouldn't make it home to the next morning. So we decided to put on a movie anyway. Mark had chosen a really romantic one for his wife and him. We pressed play and it started with a really hot, steamy sex scene. Mark and I were sitting next to each other on the sofa and he put his hand on my leg, moving up to my thigh and inner thigh. I didn't really know what to do, all I knew was that it felt so exhilerating! He started playing with my privates through my knickers and then moved to my breasts. We were making out at this stage, he removed my shirt then my jeans. I took off his shirt and his jeans also. I then took off my bra and knickers and he started playing with my breasts and fingering me and eating me out. It felt so good! I sucked his cock then I sat on him for a rough ride, we had sexy for such a long time and it felt so good! Best sex I have ever had! Every second night since then we have found an excuse to get together and have sex again. He wants to keep it a secret from his wife, but I feel so terrible. I want to break up with my Lachie for his dad. But I don't know how to, because Mark has a wife! Help me please!