My ex is now dating my friend

Relationships are complicated. You tend to hook up with people you see a lot of - often this means friends end up dating their friends´ exs. If you´ve broken up with someone, it can be incredibly difficult to now have to see this person hanging around with someone you are friends with.

First off, realize that this happens to a *lot* of people and that it´s normal to feel hurt and betrayed. Give yourself time away from them to cool off, and to regain your own self esteem. Your friend should realize that you need some time to yourself while you get over the relationship.

You broke up with your partner because you were not meant for each other. Find someone you were meant for, and hopefully you can stay in touch with your friend, whether or not he/she ends up staying with your partner.