Going against what others have said here.. From your ex’ perspective, this will obviously look as if the “mental and emotional abuse” is continuing from your part even after the divorce, unless you live in a tiny town. His coworker? Before the divorce was even finalized? Come on.
Unless he is repaired completely he’ll obviously view you as a psycho ex. He’ll be destroyed, mortified, humiliated, betrayed, terrified. The “it just happened”, “i didnt mean to hurt you” story won’t cut it.
This looks so bad, no matter if you had bad intentions or not. He’ll be terribly hurt and stuck seeing the guy’s face everyday, no matter your intentions.
Want advice? Your new boyfriend should probably change jobs. And if you have an ounce of consideration for your ex, you could make sure that he never finds out, leaving him some time repairing himself from the divorce.
Sorry to be harsh but this is way against my personal values. YMMV