no matter how unfaithful your spouse is. if you love them madly its hard to leave them. so each day you pray may be this is the day they will change and come back to you but they don't. 

listen girl my advice don't divorce him now. after leaving him you will be broken and ruin your life. give some time to yourself be prepared to live your life alone. stay with him specially if you have child (I guess you have). live with him but don't expect anything from him be selfish, be mean, don't listen don't judge. just carry on with your life. make him realize he is missing something not you. When you see that you are mentally enough to handle your life or you kids can understand why you are separated then you can divorce. Even if you divorce right away it will not change him rather he will be free. So take time to take any decision. Be strong and God will be on your side. 

God bless you