Stalker Ex

I Got This Ex Who Keep Stalkin' Me ... I'm Taken Now , And He Didnt Choose To Stalk Me Until I Got Into A Relationship. I Can't Just Keep Him Out My Life B/c We Go To School Together & Have The Same Classes. I Block His Number From My Phonee & He Calls Me From Another Phonee. I borrar Him From My friends And He Talks To Me Through His Friend's Account. I'm Tired Of It Now ... What Should I Do?