What do I say to him when he says "why are you bringing up stuff from the past? We've had good times since then and what good does this do now?"
I would stop being so open with him. That is one of the many regrets I have with my own behaviour in my abusive relationship. I was open and honest and he used it against me, sometimes storing the information for years. We had good times too, they are what keeps you holding on, hoping that 'this is it, they've changed'. But they don't.
He has called me a bully in the past! I hardly ever use that word and if anything he is the bully! - projection - they accuse you of doing the things they are doing to you.
He sounds very like my ex (they all think they're so special but really they are all the same) - couldn't take criticism (mine could perceive anything as criticism if he was in that frame of mind), everything was my fault, never took responsibility for anything, also did the muttering thing, also left me feeling exhausted. It is exhausting living with an abuser.
I want to be me again and I want to feel free.
You can. With the right help - Women's Aid - and support you will get there. It is SO worth it.
You will probably find your mental health improves greatly once you are out of the relationship. Does your GP know you're being abused? If not it would be a good idea to tell them, they should be able to help you get the right support and it won't do any harm to have it on record.
It's a lot to take in, the answers when you start a thread like this. Take you time to let it sink in and have a think about your next step. Be careful that you don't let your husband see any change in your behaviour. When they feel you start to separate mentally from them they can either start being super nice (it won't last) or ramp up their abuse.
I'm sorry you're going through this, please keep posting. Many of us have been there so have an understanding of what you're going through 