I split up with dp (and father of my children) 12 years ago and have sole custody of children. FWIW I think he is a horrible, aggressive and very limited person but have tried to stay on good terms for the children.
After we split I let ex stay in a second flat I own in London to help him save up for his own place. He ended up staying for 10 years - I wanted my children to have somewhere nice to stay when they visited him and to give him the opportunity to get back on his feet and I became resigned to the situation. In that time he saved nothing (because he is awful with money) but bought man toys of course and I lost what would have been a lot of rental money. I finally asked him to leave.
He is now in a shitty rental that is going up in price and has developed serious health problems. Hr has a senior job but worried he will lose it and won't get the flexibility needed for his treatment. He has asked for my support and to move back in to the flat. It is vacant as I was planning to sell it.
I know the Christian thing is to help and I know he is my children's father but he has squandered money, has given me the minimum required for child support, took advantage of me when together and cannot save. Once he is in he will never leave.
On the other hand my children will never forgive me if he gets sicker and can't work and I don't help him.
Aibu to say no?