My ex has got a crazy idea that I'm saying stuff behind her back and she's sent me texts like "If you don't pick up in ten minutes, I'll give you a black eye when we get to school" and " I know where you live don't forget that. I wouldn't mess about. You know i keep my word" and she's even got her dad to text me, saying " she's ill. whatever you're saying, stops now", even though I haven't had any contact with her, or even mentioned her, since we split up. So I'm pretty scared and she's trying to convince me I'm the bad guy. What do I do?