"I'm sorry but I can't continue doing this. You are sleeping with someone else and I respect myself too much to open myself up to catching an STD. And this is just emotionally draining for me, I can't handle the roller coaster anymore. It's time to bring this to an end."
Actions also speak louder than words.
Only you know where your boundaries are. You can set them where ever you want. It is all about how you let other people treat you. How you teach people how to treat you. Your boundaries are to protect you.
"What is best for my kids is best for me" Amor Fati Link to quotes: https://www.divorcebusting.com/forums/ubbthreads.php?ubb=showflat&Number=2879712