if he broke YOUR heart, you shouldnt worry about him at all. he doesnt even have a say in this. go and try to make yourself happy, dont mind him.
It all depends on who broke who’s heart, how long its been, how good of friends are they and how good of friends are you and your ex. If it seems right, go for it, dont think about “do i have a chance” because you cant put yourself down like that. Remember any guy would be LUCKY to have YOU.