感情求助

hi everyone. I hope that I can get some of your help about my relationship. My boyfriend is an american, so I can think maybe people here are know more about western culture and can advice me?

We have been dated about two years. We loved each other very much. I can not image that I could find another one would love me that much.

However, I am always bothered by his health problem. He had a major spine surgery also some serious depression due to some unfortunate event. He has to take medicines everyday for the back pain and get his depression under control. For the moment, I do not see any of this influence our relationship. But I am really concerned about the future, and about having kids.

He mentioned to me last week that he wanted us to consider engagement. I was stunned. I think i have been trying to avoid his health issues, and now I have to face it. I told him that I want to think about the relationship, because I didn't know if I can committee. I did not mention specifically the reason of his health--i think that I might hurt him.

My heart aches when I think of losing him, then my sensetivity tells me I need to be responsible for my future. I feel very confused and indecisive. Can any of you give me some advice or share anything you know about depression? In the case I had to break up with him, should I tell him honestly it was becasue his health? He always expected us to stand by each other for whatever happens.

Thanks so much.