Also the ladies of the forum think she is up to something odd – listen to them, they are better at this stuff than we are!
I don’t know, there are numerous scenarios.
1) She’s dying and genuinely wants to make amends with people she’s wronged – it may have been a long time ago, but if you’re faced with mortality you are more likely to look back and think about things you particularly enjoyed or regretted. She wants to shuffle off the mortal coil with a clean conscience.
2) She’s dying and doesn’t have many friends or family, and is reaching out to anyone who she perceives shared a significant part of her life with, just so she doesn’t die alone and unnoted.
3) She was curious about the OP so hunted him out on Facebook, and got offended/overly curious when he rejected her friend request. She made the story about dying because she wants him to accept so she can dig into his life, just because she’s a weird stalker. Because let’s face it, the request of a dying person is a bit hard to ignore, and a bit hard to accuse of lying.
Ultimately it’s up to the OP – which of the above sounds most like your ex? Can you live with ignoring her request if she is genuinely ill? If you have a current partner, what do they think? Their wishes should come before an ex of 20 years ago, even if she’s dying.
Another thing to bear in mind is that she’s called you her ‘soulmate’ – seeing her might actually might make things worse for her, because you’ve moved on and it sounds like she wants more than you’re able to give.