I'm so sorry you're having to deal with all this. Yes, this is normal for a person with depression. It's very frustrating for YOU because you can't get him to do anything -- especially anything that is good for him.
There really isn't much you can do if he flat-out refuses help. What he needs is therapy -- he needs to see either a psychiatrist or psychologist to deal with this awful depression that he's suffering. Depression is a terrible condition, and it affects every aspect of his life -- and yours.

It also affects the whole family!
I suppose you can threaten him, but that will probably make him dig his heels in every deeper and continue to refuse help.
Perhaps if you offered to go with him for couples counseling, he might go. That's worth a try anyway. Then when he sees how "off the wall" he's become, he might agree to individual counseling after awhile. Ask him and see -- who knows, he might agree.
Otherwise, I really don't know. If he won't see the doctor, then he may not agree to anything but this might work. Give it a try -- you both could use some counseling so maybe couples therapy would work. I wish you the very best. Please let us know what happens, ok? We DO care!! God bless and please take care. Hugs, Lee