If someone damages your property they are on the hook to pay for it, but if someone does something to fuck you up mentally that's now your fault and on you to fix.
I do totally agree that it isn't your fault. Trouble is, I expect there will always be bullies and narcissists out there and it's debatable whether they will ever change.
Even if they are caught and berated, the damage has already been done. Hate to say it- but- while it isn't our 'fault' it happened in the first place- it's how we keep processing it there on that determines just how damaging it will be I suppose.
It isn't fair at all but it can ONLY be on us I suppose to seek out help to try and lessen the impact- no one else can reduce that pain for us. Especially not the perpetrator who may always be a bully/ narcissist and never admit responsibility.
I speak as one who largely 'failed'. I grew up with someone I'm now certain was a narcissist. They were primarily the reason I wanted to CTB when I was 10. I suspect a lot of my 'abnormal' behaviour now is as a result in part to all that. Mainly because I didn't do the work. I just retreated further into my shell and developed various obsessions to get through life.
I'm sorry- you have been the victim of someone shit. I hope you can find ways of dealing with it. Not because it's 'your fault' or 'your responsibility'. At the end of the day- it's your choice. More because you DESERVE to live a happy life and you DESERVE to get over whatever this person did- and you might not be able to do that by doing nothing. I wish you all the very best. Hugs