You have placed a deposit, but you have not piad for the answer yet. Let me ask you a couple of questions
What kind of work are the two of you doing?
What is he depressed about?
What type of behavior?
Real, for some reason I have not been getting your responses. I apologize for the delay, and I strive to make every customers experience here a great one. Because of the problems we've been having, I am going to see if I can get you a $2 refund, if that is ok with you (as long as you are satisfied with my answer, of course)
As for your relationship, he is asking you to overlook his nagging as his previous partners have done? That sounds very arrogant, ie; ignore me while I torture you. You said you do not feel willing or able to do this, so let me ask you, if it wasn't for the job, would you leave?
No one deserves to be treated badly. ESPECIALLY when they are going out of there way to help someone. Unfortunately sometimes when people know that they need you or depend on you, it can make them even more difficult to get along with, or make them treat you even worse. Maybe that's the case here and he's angry that he has to depend on you. You've asked, what is reasonable to expect of him? It's reasonable to expect that he will treat you like a human being considering how much you've been there for him. The fact is, you've supported him and yet he still continued to treat you badly, perhaps what he needs is for you to bail on him so he can truly understand what you've done for him. If you leave, nothing will be your fault, because you tried to give him a hand and he pushed you away.The best indicator of future behavior is past behavior, and you've told him how you feel, to no avail. It's not likely that he will change anything since he's already made excuses for his behavior and basically told you to deal with it. It's only left to you to decide if you will.
I welcome your thoughts, let me know if you want to talk more.