I'm very sorry you find yourself in this situation, I don't know enough about things to offer much in the way of advice. I can tell you what it has been like for me (the one with the depression) and to a lesser extent what my wife had to go though. There are however significant differences from your husband's circumstances.
For a long time I did not have the correct sort of treatment and kept on getting worse. I struggled at work and basically had no time, energy or mental resources for anything else, including family. I was withdrawn sometimes resentful and was cut off from myself. By that I mean I'd no idea what I liked or did not, what I wanted or if I loved my family. In fact I'd no idea if I was even capable of love.
This continued until I was no longer able to work. However after a fair about of time with medication and therapy and hospital I started to improve. Despite setbacks that improvement has continued until I was back in a loving relationship and leading a pretty reasonable life.
My wife had to go to work, look after the offspring and all the usual domestic matters, plus me. She was very much in limbo and at least at the start tended to blame herself. In time she adapted to my behavior and was able to be there for me. She did have a lot of help from her mum, which made a huge emotional and practical difference.
So at present your husband is not really under the same level of treatment (incidentally psychologists cannot prescribe medication, though I suppose they might have opinions on its desirability.) At present you husband can still maintain work, and has shown an interest in a colleague, something I was never tempted to do.
This might give you some idea of what depression can do. As I said my wife had her mum, is there anyone there for you?
Being stuck as you are, not knowing if your husband will return or be his old self is so very hard. All I can say is that sometimes we take ourselves for granted and assume we are a limitless well of strength, something sadly not really the case.
I do hope you come back and talk more