I am so sorry for your troubles, and you are not alone.
I had a similar situation last Spring, and ended up in the psych ward due to the stress.
Other neighbors and people-even my husband did not understand how personal of a violation this can be, when you have had traumas and this type of situation where someone is personally violating you by trespassing and damage to what you love brings up memories that should be long forgotten, but are not. So I understand.
I am bipolar and have PTSD. I am having financial problems now over this, but I decided to give up for my own sanity. I had to decide to be right, or to be happy.
I can relate to what you said about walking the pony and the stress you felt just being outside, I go through that to.
I put up a fence, and things are better. If I see them outside, I go in. My home is my sanctuary, and they can't destroy that.
Do what is in your heart, but weight the cost. What type of outcome are you hoping for? Is it worth it? If they haven't changed their behavior now, do you think they ever will?