Hi Allycc, welcome
A ticklish situation.
The short answer is to take out an AVO against him which is a little messy with paperwork back and forth then court. But you have that right.
The alternative is to find a cafe and invite him there for a serious chat. Lay it calmly on the line you want no contact.
What you do is what Tony has said, plus I would be blocking his phone number on your mobile and if you have a landline, then do exactly the same, that's not hard to do.
If you do receive any letters from him, please don't read them, tear them up and throw them away,'what's been done has been done', it's unfortunate and sad for you, but you don't want to be telling him anything about yourself now, you don't know what he will tell other people, especially trying to win the friends you both knew, but remember some of these