I'm so confused

Okay so my ex fwb and I don't talk anymore but we still have eachother on snap and we have eachothers phone numbers. We literally haven't talked for months since he saw me on a date with someone else. And he's seen us together a couple times (me and my now current bf). What I don't understand is what he's trying to do now. He called me once. And then two weeks later he looked me up on Fb and added me and messaged me on there. We have no mutual friends so he had to have searched me up. And why message me on there ? When he can just text me ? I seriously don't understand why he's hitting me up on Fb. And he's barely saying anything in messenger either.

Also... ahha a little back story. Me and this fwb, were a thing in the sense that he said he wanted to be something more but then would kinda dub me when I was away at school. So I ended up finding someone else. Idk if that is relevant.