Caught my husband!!!

I caught my husband talking to another girl. So about a week ago I saw his messages and had messages from this girl the girl literally threw her self to him because. She start saying how’s there baby was so big so on, ( FYI she has a 3 or 4 year old child and we have at 9 month old baby). Then he mention to her that he was in her house just recently because of a party. (note: I was in that party too he never told me he knew the girl who lived there.) she told she didn’t live the no more only her mom. He ask where she live and said why didn’t she invited him over. She mention she had a bf and she then started talking bad about her bf of not being a good one. The he said. “You see you should’ve stayed with me” then. She said well you left me. They he said Would you would’ve marry. She said yess too. Then she started to talk about her car and again my husband said you should’ve stayed with me and you wouldn’t have car issues. He ask to talk in Snapchat in which from there the conversation kept going. I found out and I ask him nicely to give me the divorce that cheating was my dealbreaker. He want to work thing out, he told he will do anything to save our marriage. He deleted her and added more pictures of our family. We have a baby together and and I have my 8yr child too. Who she loves him soo much. Now I’m so confused idk what to do. Any advice?