Have you discussed the situation itself (not just the feelings) and asked her when these feelings began (and why)? Reading just your one side, I think I would feel uneasy too, your wife's moods seem to be roller coasting. That's not really "normal"? Has she seen her doctor lately or does she have anything to say about why the feelings "now" or anything so you can understand where she is coming from? That's not an unreasonable desire on your part, to get some sense of why/where these feelings of hers are coming from.

She may not want to stay with you because of your depression but I don't know that you'd want to stay with someone with whacky now-I-love-you/now-I-don't expression of her feelings?

A conversation shouldn't be one-sided and none of it is about "love". It's about the marriage and working together. You may/may not love her always (you can't tell the future) but sounds like you're working on expressing your love with her. I don't see what she's doing/working on.