Can't trust my husband

My husband and I were TTC for baby #2 when I found out he has been talking to other women on the internet and using a fake name so he doesn't get caught. He did the same thing 3 years ago, I forgave him but he obviously didn't change his ways and admitted to cheating on me once early in our relationship. He's told me multiple times how sorry he is and genuinely seems to feel bad for his actions but I think it is just because he didn't think he would get caught. The thing I'm struggling with is our son who is only 1...it breaks my heart that he may not grow up with both parents around all the time. I'm really struggling with the thought of splitting my time with him. I'm also devastated because I really wanted another baby. I don't know what to do.