Affair with borderline - help!?

To put it bluntly, this person needs serious help. She's wrong if she thinks otherwise. To be truthful, I'd stay out of a relationship with her. First of all, 15 years is a big difference. Secondly, she sounds pretty unstable. I've known people with bi-polor before, and it's hard. Their emotions go up and down like crazy and people are bound to get hurt in the process(no offense to any sufferers out there, just saying from experience). Then taking that she thinks you may just be a by product of her mind? If you stay with her, your going to get hurt. Bad. You may be indecisive and keep thinking back to the good times, but you have to really weigh the cons too. And those are BIG ones.