Is there ANY way possible you could talk her into "family counseling with you. I know it might be difficult but I was hoping that she might want to repair the relationship she has with you, and going to therapy along with you would be a good way for a therapist to get a good "look" at her, and perhaps HE could get her to come to individual sessions with him.

At the same time, he could work on the both of you to repair what is going on between you. I know most of it has to do with what is going on with HER, but he might have some ideas. She sounds like a very strong-willed woman at the present, and I just don't know how you're going to get her to go right now.
It certainly does sound like she's got something going on, as most people don't want to push everyone away -- whether she's severely depressed, it could be.
But unless she agrees to some counseling I don't know what you're going to do! I hope some others here have some ideas because I don't seem to be able to come up with any. With any luck, they'll chime in -- God bless and please take care. Hugs, Lee