My boyfriend cheated on me

So yea I found out about two weeks ago, he down played it completely saying it's all her. I get a text from her yesterday saying it was all him with a story. Idk they way she described the story doesn't add up bc I know him. But I could bc making excuses for him bc I love him. I don't know what to do I still love him but I can't trust him now. I want to believe him