She has texted me, maybe about 10 times but really don't know. I have lost count. They have always been abusive making out that I have been a complete bitch to him. A friend read a couple of them and confirmed they were abusive. Then I used an app to block them from my phone, but it still indicates when she has attempted to contact me, even though I can't read them. Each time I then contact my (ex) boyfriend, as it is clear that he has been telling her about me, as I have no contact with her since she started sending me abusive texts.
I have never changed my number, as I don't see why I should have to.