Forget Trash Talking
A date is not the time to trash-talk your ex. People don't want to hear it. It's not that you can't share anything about your former relationship, but that starting a new potential relationship off with a bunch of negativity is a sure way to get yourself hurt — and dumped.
Clear your life of as much negativity as you can — negative thoughts, feelings, and habits. All they will breed is a new negative partner, which is not what you need.