Ex’s girlfriend is harassing me

TRIGGER WARNING: I discuss mental health and suicide in this. *************************************************************

So around this past May my on and off high school boyfriend of five years and I broke up. He had been cheating on me for a while but would tell me I was crazy and obsessive when I would see signs. I’ve always had trust issues and struggles with mental health so I thought maybe I was projecting my insecurities and just expecting him to cheat on me so I would push the thoughts back every time. Well this past may (same month as the breakup) I had a huge panic attack and my depression got horrible and I attempted to end my life after the attack. I ended up being taken inpatient at a hospital dedicated to mental illnesses. While I was there I would talk to him and my mother every night when we got call time. He was so glad I was getting help and so supportive, everything seemed fine and like it was all going in a good direction. After about a week at the hospital and what felt like a thousand doctor and therapy appointments I was sent home with a diagnosis of generalized anxiety disorder, and major depressive disorder with manic tendencies. After about a week I was starting to Re-acclimate my self to being home and starting to feel more comfortable. I still felt suspicious of my then boyfriend who I was sexually involved with so I confronted him about it and the conversation went as follows;

Me:”so I know what’s going on.”

Him:”you do?”

Me:”yes, I know about you and xxxxx, I’ve suspected it for a while and I’ve just had a lot of time to think the past few weeks.”

Him:”how’d did you find out?”

Me:”I didn’t I just suspected after every little thing I had noticed over the past couple months.”

Him:”okay that’s good that you know then. So... if you’re fine with it do you think maybe you’d want to all get together sometime and mess around?”

Me:”excuse me? Hell no! I don’t want to have a threesome with the girl you cheated on me with and you should really watch out she is 15 and you just turned 18( in my state 16 is the age of consent).

Him:”okay then bye”

Haven’t talked to him since but here lately, mine you this all went down in May and it is now October, my car has been getting pranked. This girl is now 16 and I am 19 so I can’t do anything about it, her parents are loaded and we live in a little town so she never and I mean NEVER gets caught or in trouble for anything. I drive to college but still live in my home town and my ex( I think her now boyfriend) lives six hours away for college. This girl has egged my car while I was at work, thrown cheese slices on it while I was at my mothers house and I’ve even noticed things missing from my car while it’s been parked at my apartment for a week. I keep my doors locked but I have a broken window and it’s not that hard to push down and slide back up when you’re done. I’m at a loss for what to do. I have an awesome boyfriend now who is so loving and kind and understanding and I don’t want to involve him but at this point I have no one to talk to about it and no idea what to do. Help? Thanks everyone, rant over.

(P.s. I know these aren’t a big deal but it’s just very frustrating to have someone mess with something I worked so hard for and I have to clean up the mess. I’m also worried that it will escalate and more things will be taken or my tires will be next.)