I'm going through something similar. I've been married approx. 4.5 years and we've been having serious problems since just a few months after the wedding. I'm here to reach out to it you need me.

I am so sorry you are going through that. The pain is horrible. My feeling in your situation is that you could stay to try and keep your family together but he is starting another one of his own and I think he will likely keep straying or leave himself. Life is not fair sometimes. I'm hurting too.

Just: Sorry about this mess. Perhaps he is a sex addict. Please do not sleep with him again in case he has an STD if he refuses to get tested and get yourself tested. If it were me, I'd call it quits and get whatever help I needed, i.e., WIC, the local food pantry, Child Support, job training, if needed, Govt. help in paying for child care and/or family help, help from your church.