Stalemate

Go and see a solicitor and ask how this can be done. You can instigate divorce proceedings without moving out of the house. I assume you have already moved into a separate bedroom, although that is not absolutely necessary.

You don't need your husbands agreement to start to carve a life of your own.
The fact that he isn't interested enough to discuss the probable ending of your marriage is telling..

I am sorry for you and wish you the very best of luck.

Does he have any other kind of problem with his mind, as well as depression? Sometimes, as people age, changes in personality can arise through various illnesses. Is this possible or was he always difficult?

If you decide to proceed with divorce, I suppose you could see a Solicitor and ask the best way forward.

See a solicitor.

Yes see a Solicitor its one way to get an idea of how to proceed, you can roughly work out your assets, just do a bit of homework so you know how you stand before trying to say anything to him. Maybe you saying you are leaving will cause him to finally talk. There are so many health problems this could be, good luck.

See a solicitor for advice but be wary of using one for the actual divorce unless you have 10's of thousands to spare for the fees. Be aware all assets will be classed as 50/50 ownership as I discovered when divorcing my ex, the house I owned outright and he'd never paid a bean for he still managed to get his hands on 25% of.