Caught my husband cheating

I found messages between my husband and another women on Snapchat from a year ago, opened pictures that werent saved, messages like "let me see your pretty face" ect. seems like there were more messages but since its Snapchat is doesnt always save things like that. I even saw a reaction comment from her from a recent story of his of when he went on vacation with his dad. this was during a time we were working on our marriage because of other reasons and he wanted me back this isnt the first time hes cheated. he had years ago and I was stupid enough to move on forgive. but now that I saw this and that he did this while he was begging for me back, im just over it. my problem is now, is that I dont know how to go about this to him.