His ex is stalking me

So I was briefly dating this guy who was hung up on his ex. She started messaging him again and he instantly broke up with me because he still has feelings for her even though she cheated on him 4 times. Anyway, I don’t know if they got back together or not, but shes trying to follow me on all of my social media accounts and I’m creeped out. How do I handle this situation? While we were dating, he told me how crazy she can be which worries me. I don’t know why she’s creeping on my socials anyway when we aren’t together anymore.