Generally speaking, I'd say caution is most advisable - as some people have already said, a fondness grown in a state of mental instability (stress, worries, etc, do count, even if you don't generally have suicidal tendencies) can be extremely dangerous. However, you do seem to have considered several aspects of this, and have thought it through carefully, which is good.
My advice is that, for the time being, you keep things strictly friendly. Give it some time, and let the friendship bloom - at the very least, chances are you've gained a very good friend indeed from this experience, and you'll not want to take a gamble and lose that as well if she says no. Once you've recovered fully, and feel as though you are under less stress, etc (for example, you might want to wait until exams and stuff are over

), if you still feel such emotions towards her, then I'd try giving a few suggestions - jokingly flirt, for example.
Oh also,
don't try committing suicide again. Seriously dude, exams and grades and whatnot are UTTERLY overrated. failure DOES NOT mean the end of the world. So long as you are committed enough, you can achieve your goals without such rubbish. (this is not to say that education is overrated however - keeping yourself informed is very important, the tiny A, B, C, whatever you get under that, however, is less important).