I think you were showing him kindness - it was about him, and you thinking about what he might need or want - it wasn't about getting your own needs met. I think it was the right thing to do, despite how difficult and mean he can be. We don't have to be 'good' to deserve compassion in difficult times.
He is your FIL too, and the girls' grandad. I hope you are able to take some care for yourself.
