There's someone I interact with A LOT who's grieving a death. The problem is that every time we talk, that person keeps turning the conversation toward that death. She doesn't seem to know where to draw a line and without any warning says really rank, disturbing stuff*.

What can be done about this? How can I set a boundary?

*I tried asking her to give me a warning before saying shocking things, but unlike most other people I know, she doesn't seem to have ANY sense of what's shocking or disturbing and what isn't.