how do I get my ex bf to stop contacting me?

[Janette]

Basically you are the insurance policy or the fall back girl, the fact that he got involved with some one new so that he could hurt you by flaunting his new "relationship" shows what he's made of & it's not too pleasant to look at as an impartial observer.
Change your sim card & get a new number if possible (worth it for your serenity) & change the privacy settings on FB plus you can also block & report unwanted contacts. Keep doing this he will soon get the message, but only if you are in earnest about not wanting any contact with him, don't be flattered by the attention it's not benign. Going no contact is the best & quickest way of recovering from a duff relationship
Be Happy & all will be well.