Do you know any 15 or 16yr olds now?
If you do, can you think about them a bit, or characters on TV?
Then compare them to the adults around you... because they are SO different aren’t they?
They are young. And vulnerable. And lovely... and gawky, and funny, and sometimes very good at acting grown up, then reverting into a giggling/morose/ door banging mess about 5 minutes later!
And that’s just what they are. Wonderful gawky difficult funny teenagers 
And we can see that, from our perspective how young they really are, even when they think they aren’t... but as adults we can see teenagers need protection, guidance and safe spaces to live, learn, grow and yes, make mistakes.
It’s so very sad you weren’t given that environment to finish growing up in. Your reaction now shows that you were betrayed back then, by the adults who should have cared for you and helped you through the trials and tribulations of teenagehood... instead they contributed to your problems, and when your behaviour showed your internal needs and distress, they failed you again, by responding in a terribly harmful way, leaving you with this hugely inflated idea of shame, and badness.
The best thing you can do fit yourself now is to FORGIVE that young girl. It’s easier to forgive yourself if you imagine the young you as a separate person outside yourself...
Forgive you as a teenager and see that incident shrink into proportion.
Re-judge it for yourself and don’t be led by the frankly disgustingly harmful reactions of your parents at the time.
Be kind and give that poor teenager some love and kindness as she struggled with the daily circumstances of abuse... that’s so damaging, you didn’t need any more damage or hurt piled on top did you?!
You might find that once you’ve forgiven yourself, putting in boundaries to protect your life and self from that gossip monger on Facebook is much easier... priority is you, and your relationships that you care about now. That’s it.
Take care, abd be kind to yourself
