Well I read the whole thread, and personally I feel that no issue is so big that it can't be worked out. But before any of that you need to step back and ask yourself, how much do you love her? do you still love her?
From the way she is behaving I don't think she has given up, she is confused, if you don't know why then find out. You need to be honest with her and yourself. if you still love her, and want to save your marriage tell her. Ask her why she is confused, depression definitely aggrivates, and amplifies the smallest problems, maybe the problem is very small after all. If you promised to stand by her through good times and bad, then you should keep that promise. If it's space she needs, then let her have it. I'm not saying that you should wait around forever, but give it some time.
How long were you guys married?
And since you know you cannot see yourself,
so well as by reflection, I, your glass,
will modestly discover to yourself,
that of yourself which you yet know not of.