I am 50, I looked after my Mum for 20 years until she died, and now I am alone, with no family and I am lost?

[jugggle]

its very difficult to stopping thinking of something that is unfair,
im not on facebook, so I can only suggest that you absolutely deny doing anything of the kind, and tell them how upset you are at the woman saying it was you that reported her.
then I would delete facebook for good.
The next thing to do is to look for a way to meet new people and look for a new way of life.
I would start by volunteer work, your local charity shops would welcome your help, and you can do as many hours that would suit you.
don't let one woman spoil the rest of your life, and I wish you the best of luck
,