-- How fresh is the breakup? -- Did you break up with him or did he break up with you? -- Do you still have feelings for him? -- Did your friend's feelings develop after you broke up or before? Were they a possible contributing factor to the breakup? -- Does he share the same feelings for her?

If you were not meant for each other and mutually ended the relationship, and you are truly over him, then why would it be a problem for him to date someone else, even if it is your friend? If this is a problem for you (because you feel jealous or uncomfortable about it), then it may be a signal that you have not completely healed from this breakup or still harbor some feelings for your ex-boyfriend, which could create a sticky situation if your friend started to date him.

The most important thing is to be honest with yourself and with your friend. You need to decide exactly what your feelings are toward your ex-boyfriend, and then deal with that as a first priority. Then you need to tell your friend how you feel about the possibility of her dating him and come to a mutually acceptable plan. While she has the right to like him, she should be respectful of your feelings and try to be sensitive toward you in how she handles it. But you also need to respect her feelings and realize that she has a right to pursue a relationship. Maybe this is the right person for her.