If he cheated on you with her then it’s a high likelihood he’ll cheat on her eventually. Be glad he’s not your problem anymore. Try to do things that make you happy, enjoy your kids/time with them. I’ve BTDT. Hugs and hope 2020 is the year for you!

Lol, my In-laws and DH still call BILs wife “the mistress” and they have been married for years. It’s one word that succinctly summarizes a persons whole character.