I had an ex call me, hysterical, right after our breakup. He was driving around in his little green Honda Civic threatening suicide. He said he was calling everyone he knew, "to say goodbye."
I called his fraternity brothers, his blood brother, and an ambulance -- all the good that did, since he didn't reappear for a day or two!
He didn't bother calling anyone to say he was OK and hadn't gone through with the deed. I don't know if I was more scared that he was threatening suicide or more angry, because it just seemed like one more move in a very manipulative game he was playing... he'd said scary things before about what he'd do if we broke up, but it was such a draining relationship (obviously!) that I had to do SOMETHING.....
I never did hear the whole story about what he did that night, but I cut off ALL contact with him after that incident. I can understand the end of an 11 month relationship might unnerve some people, but threatening suicide was going a little far. I suggested, as gently as I could, that he might want to seek outside help, and that I thought our attempt at "friendship" was making things worse for him.
Of course, then he post-stalked me on GC for awhile -- he'd leave scary messages on my phone almost a year later if he saw me post something about "I met a really cute guy tonight...." or even "went out with the girls from my pledge class last Thursday, we had the best time...." I ended up changing my phone number, email, everything.
Now he's dating a younger girl in my sorority. The best part? She's really mad -- a girl younger than HER is dating her former exboyfriend (who's in the same fraternity as the suicide threatener.) The younger girl is a friend's great-grand-little, which is how I heard about it -- what else could I do but laugh?!