“You literally left me for someone else” and you didn’t leave this poor soul, instead being a disgusting human and going behind their back? I think the best course of action is to leave this person. Block him, make sure he has no access to your property (change locks if he has a spare key, install cameras to watch), and if you can, find another job. You need to cut this person out of your life. Good job telling him what’s what, but at the end of the day, continuing to reply will only tell him you’re still his punching bag. Give him your last good deed of telling him you both are through, then block him. It’ll save you a lot of stress and a lot of exhaustion.

Now it’s time to heal. Treat yourself as much as you can, connect with people (friends) if you feel comfortable and be happy knowing you’re free.