Guy won’t let me go, when is it considered dangerous and I should go to authorities?

I was a barista at 23, I’m 26 now. I served this guy (27) coffee 5 times, chatted for a few minutes each. He followed me on social media and tried to ask me out but I declined since I had a boyfriend. In the years between now and then, he has popped in and out to check in and ask me out. A few times I was seeing someone else. We have talked a little online and texting but nothing substantial. He’ll see me on dating sites and ask me out. If I decline he gets angry or upset and sends me long winded messages about how amazing of a guy he is and I would be stupid to decline a date from him, and how perfect we are together.

The last 6 months or so it has been this back and forth. I have blocked him twice and he will find me on new accounts he makes. He’ll get his hopes up that ill accept his date (I’ve never been mean to him, just direct and honest), but when I don’t, he will turn belligerent (say im nothing but someone guys fuck, I have no qualities) or sad and send me a string of messages describing how much he loves me, how much heartbreak I’ve caused him, begging me to give him a chance, he says he can’t date other women now knowing I exist, we’re perfect for each other, he’ll compare himself to the guys I’m dating saying he could kick their asses, f*ck me better than them, how much more successful he is than them. Most recently he even said how much more attractive and successful he is than ME and how dumb I am for not accepting his date. He has said he’s cried nights because of me, he doesn’t even want to go on living, he said he wants to find the current guy I’m dating and put him in the ground. He somehow knows I live with my parents and I don’t know how he does.

What do I do here? I’ve been direct- I’ve told him we will never have a future, I do not feel it for him, etc I’ve always been nice. I’ve tried blocking.
Updates
+1 y
I realized I don’t have his last name... it’s not on his social media. Can the police still figure out who he is based off a phone number and photos and a first name?
Guy won’t let me go, when is it considered dangerous and I should go to authorities?
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