WOOOOO, GIRL, I AM SO GLAD YOU BROKE UP WITH THAT FOOL!! Hun, your past threads on that asshole were PAINFUL to read.
Anyway, I do think it was unnecessary of you to runtelldat to your ex about your crush. You've got to understand this guy is now your EX. Meaning he is no longer entitled to any investment in your life. You're paying attention to a new guy now so he should be someone you're looking for. Keep your eyes off guys of the past who have wronged you.
It may feel satisfying to gloat to a sh*t ex that you're moving on, but at the same time, you're giving them your attention to do this and it tells them that they still matter. Whether its positively or negatively, attention is still attention. Your ex wanted more attention by starting drama with your crush to sabotage what you two share! Also to maintain control over you!
The sweetest revenge is to forget someone who wronged you and live happily without them. TRUST.
Don't bring up your ex to your crush. Don't talk to your ex, he's an ex.
You and your crush are still hanging out which is great. Continue. Be normal. Do the basics of courtship. You don't want to suddenly get overzealous and overly-doting. That would show desperation. Keep cool and flirt on~