Hmmm. Yep. He's working really hard to convince you of something. What is that? Do you trust him? Has he changed?
As far as the grief goes, well there's a lot of grief in ending relationships. For me, when I'm in the kind of pain you're describing, its' because of my unresolved ACOA child hood issues. Got nothing to do with AH. Just abandonment issues. Desperation. All kinds of memories of wanting, desperatly wanting my parents to love me. And they didn't. They were too sick and in thier own addiction. They didn't protect me, honor me, support me. They hurt me again and again. That's why I chased after my AH because if I can make him love me, change him, I'll be ok.
I may be totally off base with this cause I don't know you're story. At all.
The good news is you don't have to act right now. Or today. You can sit with your feelings, sort them out. Or go do something that'll make you feel better. When I'm triggered like this, I have to snap myself out of it with exercise. Lots of it. Then I can think clearly and respect myself, believe in myself, believe truly believe that I am happier without him.
I hope you feel better soon and will be thinking about you. You're not alone Girl. I have been in your shoes. For years, I say.