There is a friend in my group - well, I guess friend isn't the right term - who once threatened to kill us all if something didn't go her way. Just a hot headed moment, right? Well she and her DH love assault weapons, and the threat contained a direct shooting reference. (Yes, it was reported as much as it could have been when it happened.)
Everyone thinks it's no big deal, but I will not occupy the same room she does. If I show up and she's there, I bail. I don't discuss it or her with anyone, because I know they'll think it's an over-reaction, but I really think she'll be violent one day. I don't plan to be there when it happens.
There's never been a need to talk to anyone about it, but as said before, it's never at formal gatherings where escaping would be difficult. I think I'd probably play my hand the same way if it were. I don't feel like I can be flexible about it, but no one else needs to know that.