As far he knows your numbers, probably if the has free time, he will just continue switching numbers and bother you.
It was dump to revale your number to someone you don't trust.
Best thing you can do, let him be. don't block his numbers and don't reply to his meassges to his numbers also don't read them
Leave at the Recieved status. Delete chats without opening them.
Pricacy / Open you photo to the public (don't have to be yours), last seen to public, status to public.
I think following these steps is the best thing you can do if you don't wanna change your number.
GOOD LUCK