My boyfriend of 6 years cheated on me?

I need an objective opinion. I don't have any family nor friends that I can talk to about it so I figured I will ask on ya. Basically, I've been with my bf for 6 years, relationship was great for about 4.5-5 years. In the past year we have been having problems. We both became alienated, we still have sex... show more I need an objective opinion. I don't have any family nor friends that I can talk to about it so I figured I will ask on ya. Basically, I've been with my bf for 6 years, relationship was great for about 4.5-5 years. In the past year we have been having problems. We both became alienated, we still have sex but the affection isn't there anymore as it used to. But here are the events of the past 6 mos: once when his friends were over, we got all drunk and he hit me. He's never hit me before or after, and he apologized and appeared sorry (that happened 3 mos ago). Then I saw a text msg on his cell to his friend saying that he had sex with a milf by walmart. He told me it never happened, that it was just a joke. Then I saw him responding to an ad on craigs list for sex, he said it wasn't for him, but for his friend (but, c'mon, I think his friend can take care of himself). Last weekend he cheated on me with a girl and I was at home at the time (he knew I was home) and when I saw them he said "well, you told me I could do what I wanted" and just continued on having sex with her. Then he cried and apologized and said that he doesn't know what has happened to him this past few months, that he's just been very lonely because I didn't pay him enough attention (I am currently busy studying for my CPA exam) and that from now on he'll prove to me that he can be trusted. And if I ever find a reason to doubt him he promises he will shoot himself and leave everything he has to me. For the past two days he's been a really good man...but, I somehow feel like I am degrading myself. I have nowhere else to live as of now, but I was thinking that maybe this should give me motivation to study harder at my CPA, pass it, get a job and move out. I just...have been humiliated enough, that I don't know whether him changing even matters at this point. I mean, cheating at me when I'm in the same house and he knows it and just going at it no matter what?

What do you think? I just need to hear someone's objective opinion. I have never cheated on him in the past 6 years...and I am 24 years old, fresh college graduate, I think even though it's been 6 years I still have a chance at finding someone who will never do anything like it to me. Or am I exagerating? Did your boyfriend/husband ever cheat on you? how did you handle it?
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