Staying in a relationship with a cheater?

So i found out my husband cheated on me while I was pregnant... he cried and told me that he was sorry... he said that he never slept with him until I found a video of him in a very compromising act and it came from this woman... this woman has a myspace and every time he goes out so does he... it went as far as one time he went out he came home with a McDonald's bag and she wrote on her myspace that she got sick from eating McDonald's that night!!!!!! I don't know what to do... he doesn't want to be intimate with me... he has all this secrets now... the other night we got into a fight and in my desperation I called her and she said she was going to call him to tell him I was "haring her"... they talked to each other like 4 times throughout the night and one of those phone calls lasted 30min!! I asked him what the hell they talked about and he said nothing... then he said that he is not seeing her anymore and that the only reason they talked is because I called her first... what do you think? please no judging... just the honest truth... what should I do? should I try to fight for him or should I go? do you think he's still seeing her?... I can check our phone records and there's no calls from her... only that night... what should I do?? HELP!!!!!!!!