My boyfriend cheated, but I can't break up with him.

My boyfriend of 2 years cheated on me with his online ex. They sexted and talked for a few months and I found the messages on his iPod. This happened about a month ago and the last month he's been absolutely crushed for hurting me and although it might be genuine him cheating put a bad taste in my mouth. When we're together I feel like everything's okay but he lives an hour away and we only see each other once a week and I used to be okay with it before but now that I know what's happened I feel like seeing him once a week isn't enough. I've developed feelings for another person and I've thought about breaking up with my boyfriend but I love him so much and I'm also scared that it'll be a mistake. What if things do work out? I'm also scared to leave him alone because I'm all he has. I just don't know what to do and any advice is helpful.