Your situation is a painful reminder that people can get used to any situation, no matter how seemingly sad or unfulfilling.
You clearly know that this relationship needs to end. But you don't seem to have the energy or resolve to end it. I can't chant a magical incantation and suddenly conjure up courage for you. All I can do is remind you that every day you're with him, you deny yourself happiness. Try to remember what happiness feels like, and try to remember that you can get it back whenever you get up the nerve to end this relationship.
You're settled into your routine, and that routine is slowly killing the both of you. Getting out of the routine, even if it's to get to a better place, is hard work. But this is work you need to put in or else you're going to forget what joy feels like. Come up with a game plan. Write out what life is going to look like after you leave your partner. Realize that the life you create is going to be a great one.
Then end things and live the way you've wanted to. Create a new routine for yourself and get your life back.