LW, I've been thinking, I know having an emotionally abusive boss was in no way anything like having an emotionally abusive H, but I was thinking about what kept me going when i blew the whistle on him. It was pure revenge tbh, and the catalyst was when one night he came over to mine and I can't remember the details of what was going on,I think he was actually accusing me of already telling somebody something & he looked into my eyes (he was drunk at the time too) and I looked into his and all I could see was black holes of nothingness, and I realised for the first time that he did not love me and that everything he said was for his own gain/manipulation etc. I think I really turned the emotional stuff back onto him that night, to test whether or not he cared, and did he hell. (sorry that's not clear - I mean I broke down in tears etc etc to try & get an emotional response from him). All of a sudden after that I was able to tell myself I hated him and all I wanted was revenge and for him out of my life. Not a healthy way to continue being of course, I worked through it & eventually forgave him (in my head of course) and recognised the parts i had played myself, but it took some time.
I say all this because you are still saying "he can be really nice and it messes with your head" . After that night I was just talking about, even the times he was being "nice" I could see right through, everything he said to me was for a manipulative reason, and I couldn't believe anything he said. Even when I read through my diaries a while afterwards I kept reading things and going "Oh right!" and seeing tons of stuff in a different way - as is already happening to you of course!
I don't even know if any of this will help because a H is different from a boss (though I was pretty heavily involved with my boss), and probably on some (weird) level your H does love you...perhaps my boss had feelings for me too in a twisted way. But it helped me to believe he didn't, because it meant...i don't know, it meant I wasn't hurting him as much. iykwim? I felt less bound to him. I had to believe he was heartless.
Of course it was several months before he was sacked and I spent all that time continuing to pretend to be a supportive friend, it stuck in my throat but it felt dangerous not to.
Also, sudden afterthought. A lot of other people's well being was at stake, we worked with people with learning difficulties, and also he had begun going for drinks with a friend of mine (i got to her quick sharp and told her the truth about him!!). So that motivated me too. If not for myself, for others. Of course you have your boys, focus on them if thoughts of self-centred revenge doesn't help!!
sorry if waffling & if all very useless...