You are on the right track that you have to consciously detach. It’s hard. He is a hot mess of very strong emotions. You are an oasis of calm (or at least good at faking it when he is around).
Self care is really important or else you will burn out. Scream and cry and punch things when he is not around. Do things that calm you with friends or by yourself. Read a book for pleasure. Take a walk in the woods. Get a massage. Go on a vacation.
Gordie 40s W 40s M20+ kids 2016 BD W fantasy affair w OM1 I do everything wrong 2017 I start to DB W says TLTL files for D PA w OM2 2018 I do LRT W drops filing and OM2 situation slowly improving