Ex stalking me from jail

Long story, sorry: I was with this man for 2 and a half years and he was always in and out of prison, even before he met me. In fact I met him a month after he was released, and didn’t find that out until I met his family. I should’ve left then. He was not a good boyfriend and I’ll admit I ignored MAJOR red flags in the relationship. Specifically his drinking. One time in the first year of our relationship he got drunk and he actually took my car under false pretenses, and went and picked up his baby’s mother one night on Valentine’s Day. He got arrested that night because he was gone for 11 hours with my car and I was forced to call the police!! Still I didn’t listen to my BRAIN and was stupid enough to take him back, and pick him from the jail. So fast forward 7 months ago, he gets out and is ordered to go to a half way, or a transition house for newly released inmates. He ended up escaping from that place and going on the run!! Within 48 hours he was arrested AGAIN after the US Marshall’s kicked MY door in looking for him. They found my address and name on the sign in books the jail keeps from all the visits. I’m sorry but I did tell them where he was, he was staying at a hotel in another part of our city. After all of that, or course he calls me from jail. He’s “sorry” he wants to be with me, and actually thanked me for “riding with him”, he doesn’t know I’m the one who tipped off the US Marshall’s!! I told him I want nothing to do with him and that I was ending this roller coaster of a relationship for good. I stopped writing him, and even blocked the calls from my phone. Now he’s harassing and threatening me through letters!! I contacted the police who told me to contact the prison, and when I did they said they would handle things but he’s still writing me. He’s saying he’s going to kill me. I also contacted the post office, but I have to do so much to even get them to hear my plight. I sent all the letter to the judge who handles his case, and she hasn’t gotten back to me. I don’t know what to do?????