This sounds awful, OP. Just some ideas:
you say "People told others awful untrue things about me" - can you ask those people who tell you what they've heard how or where they heard this?
The things left at your house: just chuck them out.
I know this might sound stupid or uncaring advice, but can you do a bit of self-care CBT - can you pretend that these things don't affect you? Pretend that a meat pie left for a vegan is just a stupid thing a stupid person has done, and that You.Don't.Care.
The problem about this sort of harassment - like any sort of bullying - is that it works "best" (horrid way to think about it, I know) when the person being targeted responds and shows their distress (I was bullied as a child relentlessly. I learned this the hard way).
So can you ACT as if it doesn't trigger or upset you?
I realise this may sound as though I'm ignorant of the deep effects of PTSD etc, but I'm trying to offer some ideas to help you, while the police e& the GP & the community mental health people can do their thing.
The thing about pretending a certain approach or attitude is that, if you're lucky, it can become "true" - you can stop caring or letting stupid cruel pranks like a meat pie affect you. You really can.
I would also suggest that you are selective about social media. I understand about them being an important form of communication, but there is a middle way between only living life on line, and never going online.
And I'd second RuncibleSpoon's advice. Sometimes when we're legitimately upset, that feeling distorts our other thought processes as well.
I think there are lots of ways you can attack this problem. The first thing to think is: that you DO have power over your own feelings. Take control of that power. Laugh in the faces of the idiots who are so pathetic they need to make someone else cry.