On one hand it’s a valid point that therapy can’t be only about one person’s faults. Therapist might ask what bothers him too and won’t just ask what bothers you.

On the other hand it’s curious that your husband focuses on your substance abuse and your mental health issue rather than in general what you might do wrong too behavior wise.

It sounds like he wants a therapist to see that you are not in touch with reality. It’s not the same as “are you telling a therapist about depression and anxiety?”. He wants therapist to know that you are specifically aren’t fully there so to speak, not just that you have mundane mental health issue.

Interesting he didn’t say if you are sharing you have auditory hallucinations. He wants you to share that you channel some dark forces or demons speaking to you or some other similar stuff. He wants therapist to think you aren’t in touch with reality plus you are often intoxicated. Pretty much he might admit he has been acting badly but it’s because he is married to a crazy person. That will be his defense

And he likely will bring it all up in therapy even if you won’t.

It’s just my thought on the matter. I hope I am wrong on this