Cheating on me with ex

I’ve been with my “fiancé” for 6 years now, and through out our relationship he’s always been in contact with his ex, he’s cheated on me multiple times with her, blocks her to only unblock her and communicate with her again. She’s also engaged herself. And our wedding was cancelled a month before the due date due to finding out he was sexting with her again. I know at this point my self esteem is non existent and I feel completely worthless but I’ve dealt with this for so long it no longer hurts me. I know leaving is the best thing to do, but I’m currently not working due to medical reasons, and the only reason I’m staying right now is because I’m going to be under his insurance and need to have surgery done.... Which makes it so much harder. I just needed to vent.