WTF!

Ok, so here's the thing: A few months ago, I started dating the cutest guy ever. Sadly, it was not going ok, because I was too busy, I had a lot going on inside my head, and I had a lot of trips to make. As if it wasn't enough, summer came up and I had to travell with my family far away and I've just come back. In the meanwhile, and as time went by, he kept on calling me, and asking me out although I told him not to because I was no good to him at that time. Despite that, I suffered a lot because I really wanted to be with him, and if it wasn't for all that travelling thing I had going on by then, I would've been with him without a doubt. So he kept on saying he loved me, and I felt terrible. After a while, I discovered he has an ex girlfriend that he continues to see, and even while he was with me. Even more, he slept with her by christmas time, while I was feeling terrible because I couldn't be with him and he "really loved me". And everybody knew about this, except me. All the "friends" we had in common wouldn't quit warning me about him, they said he wasn't serious and he would never be. I wouldn't believe them, of course, I was too blind. But when a very close friend of mine seriously told me about that ex-girlfriend and the passed christmas events, I just couldn't bear it anymore.

The point is, yesterday night he came home, no warning at all, presented himself to my parents, and asked to talk with me. He said he didn't do all that stuff I mentioned before, and that he wanted me to give him another chance. An oportunity to demonstrate he really cares about me. But what should I do? Should I believe him and start over again, pretending none of this has happened? Should I just cut it off and stop seeing him, tell him it is completely over and try to forget about it? Why are men so complicated? It was really simple indeed, to tell me that he was no longer in love or whatever, and go fuck his ex-girlfriend in peace. Either I have the worst luck ever when it comes to guys, or this particular guy is an ashole.