I think it's important to highlight here that even if sex addiction was a thing, which I don't think it is, what he does to you is not sex because it's coercive and it's not based on real consent. So he's really just saying he's addicted to control and pushing your boundaries and I think THAT is true. In the sense that this man is so deeply dysfunctional that nothing will change. Even if he wanted to change, truly wanted to change, no mental health professional would ever suggest it should be attempted while you're with him.
I truly understand why you would try to hold onto hope that he might suddenly wake up and change. I am a mental health professional and as such I always try to work with people no matter what they present with. But you're not his therapist, so you should absolutely not have that attitude and hope because to you, as his wife, it is harmful. I understand why you would suggest to him therapy, but it is really not clear to me that therapy could do anything here. Being an abuser and rapist is not a mental health condition. If he told me what he did to you I would have to report it. It's entirely possible that he has some personality traits that could fall under the umbrella of 'mental health'. But I'll be honest with you, men like your husband we usually only ever see for therapy in prison settings as part of their treatment order. Although we try, the probability of someone like your husband, at his age, getting to a point where he can be in a healthy romantic relationship is so close to zero that really, our aim is future harm reduction. People who commit such violent to the person boundary violations and crimes will usually fall somewhere along the antisocial personality disorder spectrum. So we try and get them to understand that for their own interests, they must act in ways that are less destructive because the consequences of their actions are not enjoyable to them. But your husband's actions have had no consequences so far, he has no incentive to stop.
I don't think you should reason with him, try to convince him, be truthful with him at this stage. I think you're in a lot of danger, and trying to assert yourself might have seriously risky outcomes. Men like him can sense when someone is pulling away, even if it's only psychological pulling away. You've been under his control for so long he knows exactly when something feels different. This is why it's so important you talk to DA services, they can help plan.
You have come so far, and I know you will keep finding the way back to yourself. The process of leaving him is probably going to be one of the hardest things you ever do. But now you also have the voices of other women to bolster you: so, so many women who left similar situations, who struggled in the same ways, who can absolutely promise you that when it's done, your life will feel so much easier.