How do I teach my Husband of 18 years a lesson, Do I stay? Do I make him leave? Or have him make it up to me?

10 years ago he cheated on me with a piece of trash chick that claimed she had a 7 year old son with him, We had been with each other for 6 years, He and I biologically had 1 child together @ that time & 1 each from past relationships. Come to find out that the kid wasn't his anyway nasty whore that she is. 2 years later I allow him back into my life with the promise that he will never do this again, Well this past summer he decided on Facebook to tell this trash that " He needs a place to hang out", and of course she says "come on, you know where I live at", (She knows about me too!) I approached him about it and he had the nerve to get defensive. Says" he never even went over there" He claims he was mad because a month earlier an old male co-worker posted Happy-Fathers Day on my wall! Ridiculous Right! Now I am not stupid or self-conscious but we now share 4 kids, He vows again that he didn't see this chick, it was just to make me jealous, and he wont do it again. Do i believe him, not really, But I don't know what to do. I can't just up and leave, financially it wouldn't be in the kids or my best interest, He is not physically abusive but I need to find a way to let him know that this will not be tolerated, and I want him to show me and our children, some type of retribution for his actions. He not only violated me But he broke his promise to our children. Any suggestions?