Ex texted me happy birthday, how should I respond?

Anonymous
He's a complete d*** and still thinks he has me wrapped around his finger, but I want him to realize that he doesn't. Should I respond with 'thanks' 'thx' (I never shorthand text, so he'll know I'm pissed off' or 'thank you :)' and what if he responds with 'no problem' .. Should I text back or no? Does that mean he wants to talk ..?
Updates
+1 y
I think I'll just say thanks, and then not respond to anything after that. thanks for your answers.
Ex texted me happy birthday, how should I respond?
14 Opinion