Why is my ex acting like a child?

Natasha
A couple a days ago, we went all out on Facebook saying that he got a new girlfriend and how he's never felt this way before, etc. it was all bullshit and I knew very well. Because it all went down yesterday, deleted. So today, my mother gets a text from a burner number, easily downloadable from the app store, saying that, "did you know your daughter is stealing your car every night and delivering drugs to boys for sex?" 
Once she told me, I have never laughed so hard in my life but it's inexcusable. What does he want from me?