Ex friend wont leave me alone after hoping to get some

I really need to get rid of this ex 'friend'. I was friends with him for about 4 years, we'd hang all the time, like best friends, and I was his best friend apparently.
I was even like his wingman when we were out, helping him get chicks. Fast forward last spring, it's spring break and him and his gf come down to visit me (we're a state away now for college) and I got really bothered by his behavior towards her and stuff, like he'd say 'oh blah blah is so cool, she's such an awesome friend, see, she's into this, and that, she's cooler than you, she likes this, and...' just making her feel inferior by stating what we have in common etc.

They left and he broke up with her and he messages me a week later asking if I wanna be his **** buddy for the summer when we both go home (note that he has always made it more than clear, not just to me, but to other friends and in front of other people that he has zero interest in me, and that I'm like a sister to him and best friend, friend zoned for good)

Either way I was weirded out by his behavior and when I told my best friend this (he's also friends with him), he said that he was shocked and thought less of him then.
I could not believe he was saying that to me after years of being friends, and I wanted to see his reaction...

I start dating someone who notices said conversations and confronts me, I explain that it was out of my shock for his actions and I block him and ignore him. I go back home for the summer and have to avoid him, he tries EVERYTHING he can do to contact me (getting anyone that knows me to ask me to talk to him, reactivate his old Facebook account and message me, drive to my house etc...), and finally (I thought) he gave up.

He messages me the other day saying that he hopes I can forgive him (note that he already messaged me saying he didn't know I was in a relationship and messages my boyfriend too, saying that he wants to get to know him etc...) I almost considered messaging him and saying I'm sorry but this has ended and he should stay with our good memories and move on but today he messages me saying I'm a hypocrite and starts insulting me and trying to call non stop and I don't know what to do or say to him? Why wont he go away?

tl;dr: Friend hoped to get more out of me, I said no and now that I'm in a relationship, he wont leave me alone.