Sept 25, 2012- I can't "just get over it"

I'm at a loss, I honestly don't know what to think. I know I should be angry and walk away, because no matter how many different euphemisms you use the bottom line is my boyfriend cheated and lied. The problem is, things are never that black and white, especially when it comes to relationship. Things get complicated, impulse takes over, mistakes are made, and despite how much we regret our actions in life there isn't an undo button. The past cannot be changed, forgotten, or erased, only accepted. I wasn't there when any of this happened, so I will never know exactly what really happened. Alex said he was way too drunk and some girl came onto him, and after they kissed he told her to stay away from him. No, I am certainly not dense and know that there is probably a lot more to the story. So now I am faced with a tough juncture. I want to forgive Alex so badly because I love him and want our relationship to work, but I also don't want him to think he can walk all over me and fool around with whomever he pleases, because in the end of the day I will still be there. I also question his sincerity, because I know Alex and he is the worlds best actor, he can lie to anyone with out even flinching. He will say anything to get what he wants, or to get out of trouble. After this was discovered and he explained his side of the story, all he kept saying was, "baby I love you so much, and I am so sorry, I wanted to tell you I just didn't want to hurt you." I really want to believe him, but sometime it is so hard to trust him when I know what he is capable of. I just don't want to get hurt, but it seems like no matter what I decide, I am going to get hurt. If I walk away from someone I love so much and he didn't at least come after me, that would kill me, but on the other hand, if I stay and it turns out I can't trust him, that would also hurt me tremendously. The worst part is today only our two monthaversary, and already I feel like this. He also hasn't even called me yet today. But I'm not going to call him, because if i am truly worth it, he will want to call me just because he misses my voice.