What if your ex boyfriend and you work together and its not working out getting back together?
If you like your job very much, i would stay there and make sure, especially in the beginning of the break-up, you wont see your ex-boyfriend that often. Maybe after a while you can handle it to see him, and enjoy your job. Or otherwise, if you already wanted another job i would get a new job. This way you will not be confronted with your ex-boyfriend if you dont like that and you sort of start all over again.