This all sounds very challenging. Hugs to you. Keep going, dear Z.
I am going to say something that may sound a little strange but I take it as a positive that your H said he fears he may be mentally ill. My thinking is, if he thought that he was acting completely normally and that his thought processes at hte moment (e.g. threatening suicide when you talk about your problems) was normal, I would be more worried. The fact he recognises he may have an issue - that's good. That's the first step.
I can't remember if you said before, but is H seeing an IC? Sounds like he has some individual issues he needs to work through.
Me 28 / H 28 M 1 / T 2.5 BOMB 12-3-14 "I don't feel like myself any more" Still living together, separate rooms.