Oh Rabble you'll get there
It is really really hard but you will. Just telling one or two very trusted people and chewing it over can help you get your head into a different mode.
I had quite a few last straws that added up to the thatched roof as mentioned above - among them:
When he shamed me in front of friends to preserve his own image (more than once).
When I desperately needed help with a work issue and he went to sleep while I was talking to him.
When I needed him to take/fetch dd2 once a month from club because I was in a different city working and he had a tantrum about it.
When I realised that the only reason things were going well was because I had stopped disagreeing with him or challenging him. (I tested the theory and next time I disagreed it turned into a row of epic proportions)
When he let me sit and take verbal shit from a family member (HIS family) in front of everyone at xmas, and I was actually defending him as part of this, and he wandered off and left me there to deal with the onslaught alone.
When he persistently, deliberately made dd2 think of me as a booby prize and made her cry if it was my turn to put her to bed.
Loads more.