It's hard to talk to someone when they're down on themselves. Comforting words are rejected, efforts to help are shot down, and your solutions are found wanting. It feels like everything you say is wrong or only makes matters worse. In reality, it's the other person who's doing this to themselves, and that won't change until they find their way out of that dark corner. This is the time for patience and leaving people alone. Trust in this, and this person will reemerge eventually ready to share and full of gratitude for you being there for them when they couldn't be there for themselves.