Honestly, Caleo that's a dodgy road x (been there, done that)
I think this is right. You sound like a lovely person, LaCrepescule; and therefore more vulnerable to being treated badly; thrown back into the water and then reeled in slightly every time you pull away; feeling it is your fault. It's good to see that you are ready to break it off, but I predict a HUGE effort on his part of reeling in when you try!
You will be much more content when you no longer have him in your life. I have had a very similar experience, and now feel much better being alone and responsible for myself. I live alone and have three long-term illnesses (Type 1 diabetes, Chronic Fatigue Syndrome and depression; I've also had cancer twice) and many people have worse I know. Just imagine being dependent upon someone with no understanding of your feelings, no empathy and with this controlling aspect to their character; I can't imagine anything worse! Your daughter sounds supportive; perhaps she could listen to your fears of illness living on your own, and may have suggestions.
Free writing might help you. You sit down with a pen and paper and start writing without any care or preparation; just write whatever comes into your head. You can give yourself a time (a minute to start with?), and I think you will be amazed at what comes up from your unconscious self! Maybe try some meditation tracks (try Ihttps://insighttimer.com/ or www.youtube.com/results?search_query=daily+calm+10+minute+meditation; there are many other free ones online). Whatever it takes, regain some self-esteem; You're Worth It! Then make the break however you can.
You will need to be super firm about leaving; please don't be reeled in again! He will try expressions of love, deep apologies; saying he can't live without you when he sees he can't control you any more. Toss back his hook and line and swim away!