I don’t even know this man!? 😔

I’m not sure what to do at this point. My husband and I are both Christians. He knows God’s word very well, but I just found out he’s been having an affair with his other kids mom. I don’t understand. If that’s who he wanted to be with why would he marry me? Why not just get back with her and leave me alone. Did he think my life was a joke. How embarrassing it is to be married twice. I can’t stay with him. Divorce is definitely something I will proceed to do. I would tell this man over and over I felt something was not right with them. He would tell me I was destroying our marriage. We would pray before dinner and he would ask the Lord to protect our marriage when he was going outside of it. & on top of that I found out a week ago and he has not said a word to me since. Does he not know what he has done??? Am I just supposed to get over it and move on?? We even have a 9 month old and his oldest daughter asked if I would be her mother because her mom passed away a year ago. Did that mean anything to him??? This is crazy. It’s like he was living multiple lives. I’m in shock I don’t even know who that guy is.