Walked out on partner while his dad is dying.

For four years I have been desperately in love with my partner. I thought I'd found my person.
A few uncomfortable things from day one whixh I thought was probably me being sensitive..or things we could iron out or simple miscommunication...
These things have now become unbearable and I finished the relationship 2 weeks ago.

The house has always been a terrible state...not just a bit grubby, but piles of washing, rotting veg, mouldy fridge etc. The loo I can't understand how it was so disgusting.
I knew he was unusual, probably on the spectrum ( I'm not picking at this...I work for thr NHS and I'm quite comfy with a range of people x) I loved his eccentricity but stress from losing his business, lack of money, his diff8xukt children along with a dying family member...it's been too much for him.
He became obsessed with sorting everything himself, wouldn't allow me to go on the mortgage, even though we were due to get married....massive depressive spiral. He won't go to the gp or access any groups. He started to say I'd isolated him, didn't want him to have friends, that I was jealous etc etc. I feel a bit bemused...I'd always noticed that he was quite easy to manipulate ( I never did...it was virtually impossible over thr last 6 years to encourage him to do anything he didn't want, Include brushing his teeth He was so low that I made an awful mistake and contacted his sister and sil for help. They now think I'm absolutely bonkers. They say basically that he is private and that they keep an eye from a distance. I should have respected this but persisted as at one point he was telling he was going to.commit suicide, he drove off twice after a row saying he wojkd be better off dead...
I've really struggled to help him. Out relationship withered away to me cutting his nails, encouraging him to have a quick shower and the odd cup of tea. In 6 months it wasn't as though I had a partner...it was like a stroppy teen.
One of the major issues was hording. I woukd have no right, in someone else's house, to expect them to tidy up or throw their own stuff away! Everyone has different standards but...his stuff smelt,greasy hand marks (dark grey ones from build up) on walls, plaster still not painted after 20 years, old love letters, notes from old girlfriends scattered about( there isn't any differentiation between this ajd a crisp Paxket or bag of old parsnips..so I don't particularly think he was holding a candle for anyone else)
Then...boundaries.
He seems to get pulled along by quite manipulative people. Anyone loud or anyone I would see as brusk or a bit rude.
He continued to say he loved me and to be patient bur at Christmas his chidlren stole off me..he did nothing for 5 days. He had wanted us to live together but this kept being an issue...I ended up in a static caravan in his garden and was very much kept there ..the whole situation was so odd. When jd ask him he woukd say he needed Time to sort the hosue out and make it nice for me and him...yet nothing seemed to change.
For over a year his dad has been dying. We have had a few calls and we have though it was the end...so,so sad. Ambulance comes out and then he peps up. He is the sweetest man and will be missed Terribly.
However, I sort of started to get tjr feeling that this was(apart from being very stressful for my partner as he would drive iver and help)
..i started to think that my partner was using this as a way to deflect any difficult conversation.
I feel like the worst person in the world but after yet another teenage strop from him, I ended it.
I asked his sister and sil not to contact me as I xoudknt keep caring for him when everyone else seems not to be worried about him. I'd wake up riddled with anxiety incase he tried to commit suicide and he had become unpredictable and I cried every day.
Why do i,3 weeks after,feel bereft without him. I'm 47 and feel like I've missed my chance and that this was my person...I've let him down,let his family down by not staying with him. I feel like an utter failure. If we lived eachother maybe I shld have just held on a bit longer... his family must think I'm utterly awful, he must do too.
I've messaged a couple of times to apolgise and then deleted it as felt it would open a can of worms. If I ever asked anything or queried stuff,it would erupt.