We talked about our future together, we got engaged, made plans for living together (sell both houses and buy one together)... Then one day after a argument, he stated that he wasn't interested in living together now.
My immediate reaction right there was "he just helped you dodge a bullet". Despite the hurtful delivery, he saved you from giving up your financial independence and your home for someone who is not 100% committed to you.
Then I read on and I am sorry, but I saw red flags galore. I will translate what I understood :
He liked living on his own, but wanted to stay engaged and continue the relationship as it was means that he wants to have his cake and eat it. He wants the comfort and priviledge of a relationship, without moving forward, evolving, or coming through on things he had previously promised (engagement, for example).
When I complain about pain or that I have medical appointments etc., he just switches off sounds as though he lacks empathy for you. This is callous anyway, but would you want to face this non-reaction if your condition worsens or you need help?
I have even said maybe it would be best if we go our seperate ways. He then gets upset and says he wants to carry on - of course he does, he's got everything that he wants/needs from you without responding to your needs. And I hate to say it, but by not making a clean break from him you are really saying "ok, I will continue to accept this situation that does not meet my needs. I may go on about it, but I'll put up with it". (Speaking from experience and I felt so relieved when I ended it).
He has also lied to me on several occasions only you can decide how much dishonesty is too much, and about what, but this is never great in a relationship.
He says if we split up, then he wouldn't have another relationship - so what? But also I hope that no one would put up with this non-engagement.
You sound like you are a lovely, patient person and you have tried to discuss this with him. Wanting to marry a partner who proposed and wanting to live with someone who suggested living together is not unreasonable. I think you will feel 100% better if you just cut ties and focus on what you really want in your life.