Disgruntled Ex Is Harassing Me, What Are My Next Steps (if Any)?

In Pennsylvania. This story is a lot. After a month and a half of attempting to break up with my (now) ex of about 2 years, I was finally able to break up with him on the 4th try. He has a history of anger issues and reactive behaviors for which he just began seeing a therapist in early April. After the break up, I left the apartment we shared to allow him time to move out his belongings. While I was gone, he took my Apple Watch and texted people in my contacts pretending to be me. I was able to get back to the apartment later that night after ensuring he was not present and got the watch back as well as some other essentials and important documents. From that time until his official move out date on 5/4, he trashed the apartment, though caused no real property damage. He’s also messaged a number of people in my life either from his own personal phone number or social media accounts saying horrible things. The day after his official move out date, I saw through the app connected to the electronic lock on our apartment door that he had locked and unlocked the door several times and adjusted the thermostat. I contacted the police as I assumed he had trespassed on the apartment property and was told by the landlord to call the police if he attempts to come back to the apartment after his move out date. When the police had gotten there, my ex was not present. I gave them his phone number, they called, and he had told them he was not present that morning and that he does not intend to return to the apartment or contact me further. Apparently he was manipulating the locks and the thermostat through the app on his phone (which I was told he would no longer be able to do, but it was a weekend, so I’m assuming the landlord just wasn’t present in the office to remove his access). After that, I received a text from an anonymous phone number saying my ex believes he left his GoPro and a clock at the apartment. I searched the apartment and could not find it, so I messaged the number back saying that I couldn’t find it but any further inquiries about the apartment and missing items should be directed to the landlords office. Then yesterday I got a text from a friend that he had messaged her on social media saying some more horrible things about me.

Though he has never made any explicit threats, this behavior is horrifying, and I know he owns at least 3 guns. After he moved out, I’m assuming he moved back to his hometown in New Jersey, though I don’t know for certain. Does this behavior qualify for any sort of legal protection?