abusive ex brought his gf to my house today

-sorry in advance if this writing sucks, I am having a panic attack-

My ex M26 and I F23 dated for six years. I broke things off last year on Valentine's Day after he got violent with me probably for the thousandth time, but it was the worst it had ever been. We had given each other our gifts, I hand made a card for him and got him some things. Honestly, I can't remember what I got him. I do remember during our fight because I asked him to not blast music at 3am he broke the necklace I made for him and threw it at me. He felt like my gift wasn't enough, that I never appreciated anything, even though I always did. He threw my stuff at me that I had in his bathroom, and I walked home from his house at 4am when I got tired of fighting. The next day he picked me up to take me to the train to go to school and I asked him to apologize, and he started screaming. He sped down the street saying he was going to kill me, that he never loved me, and he was hitting himself/me. For about four years he would scream at me in my face like that, threaten to crash his car while driving, and get violent with his parents then blame me or his sister. He had assaulted me towards the end of our relationship and after the fight last year- he even had gotten so violent with his sister and I that we had locked ourselves in his parent's room when they went out of town. He had broken the door down to hurt us because we were "too loud" during a sleepover. I don't know why but, something flipped in my head, and I left him. He had screamed at me outside my house and threw me against the door. I had barely gotten away from him. Now seeing him drive by my work or seeing her tweets about how she wants to "run me over" send me into panic attacks. I had left some books at his house that I told him to just throw them away. Tonight, he brought her to my house to drop them off and he gave her my phone number to text me about it. I told her to leave me alone or I will go to the police. They just won't stop. He still calls me crying begging for me back off of fake numbers. He texts me off of fake social media accounts. Every time this happens, I hurt myself because the panic attacks are just too intense to deal with. I don't know what to do anymore. It feels like the only way to truly be free from him is to kill myself. I blocked him on everything, and I am in the process of changing my phone number. I don't understand why they won't leave me alone. Yesterday was Valentines Day... Why am I the most important thing for them to bother the day after they should be celebrating their love together. Is this enough for the police to take me seriously? I don't want to be laughed at in the police station...