Why is my ex talking trash about me?

Natasha
It's been nearly two weeks! Leave me alone. He's calling me a stalker, texting my mom telling her I sneak out in the middle of the night to sell drugs for sex and now he's saying he's looking back with disgust. He's the one faking a rebound relationship, saying he's going places when he hasn't even left the house...  every time he makes a mean remark, he deletes it after 20min 
Is he just saying this stuff to get something out of me? When we were together, he and I couldn't get our hands off eachother... but what he's saying now doesn't match up to his actions before... like past text messages and feelings. the reason why we broke up was his fault. He's the one with the drug addiction, has the DUI and is mentally unstable. Why am I getting the wrath? 
He blocked me on facebook. I don't even use facebook. I'm a Twitter person, he doesn't use that. All my stuff is public on Twitter. But it seems like every time I post something on there, he posts something that kinda reflects on what I had to say. I'm not stooping to his level. I'm trying my very best to ignore him, I really want to fire back at him over text but I know that's what he wants. He's acting childish and immature, I do I deal with this. I don't even know for a fact if he's reading my stuff on Twitter.