Don't make the mistakes I did.
I chased and begged and pleaded my older dcs dad for contact, even paid his expenses to come see them multiple times.
He would show up, then piss off again for months at a time.
I thought a shit/part time dad was better than no dad. I was very wrong.
All it did was confuse my kids and make them feel rejected over amd over again.
They are adults now and been totally nc with him for years, and I've apologised and explained my reasons and what I should have done many times now.
I get that it's hard op, I also have ND kids. SS are really crap with the support they are supposed to give parents of kids with disabilities. Get yourself on some groups, contact some charities, speak to other parents and see what is available in your area for a bit of respite for you. You could also try your local council, my dd has funding from them for me to get respite for 3 hours per week (although I live in the back of beyond and there's nowhere to spend the funding unfortunatly). Speaking to other parents in your area can be a game changer though, there might be options that aren't really advertised for you to get a break.