I'm sorry you're feeling low today. He doesn't seem to understand, nor want to, I agree. I don't understand why anyone would be in a relationship and think they do not need to give support. That's part of it, surely?
Also, even though your depression pre-dated the relationship, what if it didn't? What if it was post-natal, or the result of a head injury? What I'm saying is that I don't think that's of any importance, and as you say, you did tell him.
Of course you can't snap out of it, and my heart goes out to you that you feel that's what he wants you to do.
From what you've said, you are trying to "fix yourself" as much as you are able, not asking for him to fix you, just to offer support and understanding along the way.
That's not a big ask. I must add, I feel quite cross with him as I write this! Sorry