Hi Janep, and welcome, I am new here to bet not new to mental health issues.
You are right though you need support too.
Firstly, let me say that there is no excuse for your husband belittling you or treating you with disrespect, and I am sorry that he is putting you through this. I am going to try and put myself in his shoes, but firstly has he always belittled you, or is it only since he developing depression or his depression getting worse. If he has always done it then he is using his depression as an excuse to get away with it.
My guess is if he has only started belittling you since his depression has increased, it is probably because he feels inadequate. Unfortunately, sometimes when people feel inadequate they find ways of making others, particularly those close to them feel also feel inadequate. This somehow I believe make themself feel better about themselves. As an individual who suffers from depression amongst other issues, I don't really understand his behaviour, and once again depression or no depression there is no excuse for this type of behaviour.
My suggestion is he needs to see a Psychologist if he isn't already, with a goal that eventually includes you sitting in on his sessions. The goal with these sessions would be for your own grief and needs in the relationship to be spoken about and addressed with the help of the Psychologist while you are both there together. This might kill two birds with one stone, by you sitting in with the Psychologist he may also open up and start talking to you through about what is going on within his internal thoughts, through the Psychologist.
Hope that helps a little Janep