I don't believe she was threatening - more telling me she thought about it. I don't know how to continue this. It's all manipulation - when I push back she out does me with things like this. (gaslighting?)
The game keeps changing - suicide now. It made me stop, pull back. I told her things that I shouldn't (I've often thought about suicide - I know it just gives my pain to those that I love so I know to look for other options).
If I'm right, you possibly save her life and the life of the mother of your children.
If you're right, worst case you've now:
a) opened up a police and most likely a medical record, which could be useful going forward; and
b) you've shown her if she's going to play that card, you're going to take it seriously. Every. Single. Time. If she's NOT serious about the threat, then you watch how quickly this will stop her from pushing THAT button again!