Guys prioritize where their interest lies not where they feel obligated.
When it's someone you consider a family, it's hard to even think they would backstabbed you esp.
I could have gone for proof but with him it was like my siblings or parents informing me about it.
Your goal is stop giving a crap what she's thinking and why she's thinking that, and to do that, you need to block her and not look at her social media or let her contact you.
Frankly I haven't had the time to go through 13 pages about her, so it wouldn't be fair of me to say anything about her or conversely to defend her.
A little bit of background on my guy.
I think if he liked you romantically at first, and you called it off, he's probably still interested.
They don't want me and don't want anyone else to have me.