Oh no, Shaden -- that's the worst!
As a teenager, about half of my friends and one family member were suicidal at various times, on and off. As a person who truly cares, you can't just ignore it, because how horrible would you feel if it was for real! At least, that's the thought process. And those people that say, "Ignore it; they're just vying for attention" sound horribly cold-hearted, don't they?
What might help is reading up on real symptoms of someone who's considering suicide. There's a really good list here:
What can I do to help someone who may be suicidal?
I wish I could give you specific advice from my own experience, but nobody tried blaming their suicidal thoughts on me specifically. I helped my friends when they needed it, but slowly started to withdraw. Most of them latched onto someone else for their pity parties. They are all still emtotionally needy people that I do not need in my life, and so I only rarely see them, and it's usually in passing.
The exception is my brother, who was in serious trouble. We found out that he's bipolar, and he was admitted into a hospital on suicide watch when we were teenagers. I was there for him every chance I got. The difference with him is that he consciously pulled himself out of the worst of his depression through weightlifting and cognitive behavioral techniques, and he tries very hard not to drag the rest of us down, not to be an emotional vampire.
So I guess what I'm saying is, if she's in serious trouble, do help her. If she
gets out of the red zone (if she's even in it at all) and she still emotionally blackmails you in smaller ways, for your own emotional health, it's probably best to reduce contact with her until she grows out of that stage (if ever). I know you still care for her -- for all my harsh words, I really care for my old friends too, and think about them often. But it is not my calling to help them heal. To do so properly would be a full-time job.