How to make things better between us?

Find another job, you shouldn't be working with a guy you broke up with and still have feelings for as it wont work out. Also, if he's married, big red flag. You should find someone single and take care not to get swept off you feet by married men or until you find out if the guy is single. There are some issues with relationship boundaries and your possible being attracted to chaos. Seek professional counseling for this and get yourself on a more positive track. Definitely cut ties with your ex asap, good luck!