OP, my friend was in a similar situation ish...but not as bad as your situation.
Years of being politely tolerated by his two daughters.
Her retirement coincided with one daughter returning to work and looking for expensive childcare for the first grandchild.
She asked dad, only, to do 3 days a week.
My friend said it was his choice but it had absolutely nothing to do with her. She had other plans for her retirement from teaching which did not involve ANY childcare.
Her husband presumed she would relent and be around the house with him.
He was wrong.
She easily made plans to be busy on those days, lunch, tennis, golf, visiting family and friends, going for short visits away.
Within a couple of weeks he was very upset, hated the commitment and told his daughter.
It was reduced to 2 days.
My friend then decided to do the Camino with friends and committed to doing overnight training walks on those days.
Her husband was very pissed off, because she was barely there.
He became short with her and cranky.
Things came to a head and she decided to go to Australia for an extended holiday and to give them both space as she felt she was perhaps done.
Australia was a great holiday and she told him she was moving in with a widowed friend.
Finally the penny dropped.
She returned after Christmas, and he was no longer minding his grandchild.
She still went to stay with her friend, but after months of him making a sincere effort they were back together.
She did the Camino with her friends in the May.
Her biggest regret is she tolerated his children for so long.
She certainly wouldn't do it again.
His daughter has warmed up considerably as it was made finally clear to her that she would only see her father infrequently at her house if she didn't.
They now take lots of trips together but she also is very very conscious of having her own friends and interests during her retirement.
She encourages her husband to see his children alone, she really has no interest anymore.
She has no interest in becoming even politely invested in his grandchildren.
She considers the whole episode a blessing.
She showed her steel and he knows that she was very prepared to divorce.
In your place OP, I would be making concerted efforts to reconnect with friends.
Plan how you want your life to look.
Organise your finances.
Get legal advice.
Make no further effort whatsoever with his children.
Their behaviour is disgraceful and yes you need to properly own that you have tolerated completely unreasonable behaviour.
Finances are key, so you need to look at splitting them.
Alternative housing, how will that work?
This is an awful weasel of a man.
You deserve so much better.
Oh, one more thing that she has decided was that her considerable nest egg is going to her nieces and nephews in its entirety.
Apparently through excellent retirement planning she is now very well set up and recently gifted her niece and nephew 10k each which her husband let slip to his daughters.
Their was genuine surprise that they have not been included in her retirement largesse.
Delusional or what?