That moment when you get a DM on Instagram from some random chick demanding who you are and how you…

Lmaoooo send her the "Congratulations, you played yourself."

I’d start with something from your childhood that would have a different meaning to her. Like we’ve slept together, met the family, I can call him at midnight and he would be right over, things like that and let her mind go crazy. It might be tough for your brother at first but sounds like he should run like hell from her so maybe she will leave on her own then