I've never personally had one incident make me want to kill myself, and as someone who used to think about it for years, it just builds up until you can't handle it anymore and just want out.

I've had one incident stop my suicide attempt, but never cause it. (long story)

As for your boyfriend, it seems he will likely need you in his life more, as a comfort, because if him and hi mom were close, he's likely hurting/missing her.