My ex will not give my stuff back

We broke up a few months ago and he’s refused to give my stuff back. For context we have a year and a half age difference so he’s 17 while I am 19. When we dated I bought a phone he could use (mind you he has another phone this was just because he wanted to speak to me when he didn’t have his other phone?? I know it makes no sense) i paid for everything, the phone and every bill, and it is in my name but he still refuses to give it back. He cannot keep it there are explicit pictures of me on there that he can’t keep because he keeps threatening me with them. He says he doesn’t want to give it back because “there’s photos of him on there he doesn’t want me having” I told him I honestly don’t care what he doesn’t as long as he doesn’t have that phone I even told him to snap the fucking thing just as long as it was gone

Here’s where it gets stupider. When we dated I paid about 500 dollars for concert tickets and we got in the very front he got a pick and gave it to me as a gift, he asked to give it back and I am not doing that. I spent my graduation money because he cried in my ear to buy the tickets and I did and now he claims “you didn’t pay for the pick you paid for the experience” I wasn’t arguing I js said I’d give it back and I’m not fucking doing that. He was a nightmare for a year and a half while dating I’m allowed to be petty abt this but if I don’t cooperate with him I worry he’s js going to hold those photos over my head again

This all sounds so stupid but he is seriously the fucking worst as long as those photos are gone I don’t care if he lives or dies.

I’d like actual advice on what to do, I don’t want to be told “you’re young it doesn’t matter” “that was your mistake it’s stupid” “why would you do that” or “just give it back” it’s not happening, any helpful advice is super appreciated I’m just really done with him and I want this taken care of so he can be permanently banned from my life