Dating a Friend's Ex
Lots of things to consider here.
How close are you to your friend? How much do you trust your friend’s opinions?
If you’re close, and your friend is not thrilled about you dating her ex because she doesn’t think he is a healthy or safe person for you to date, proceed with extreme caution. If she thinks her ex is a cool, and they just didn’t mesh well but you might, go for it!
If your friend prefers you not date her ex, because it would make her uncomfortable or because she’s not over him, you’ll have to decide which relationship is more important. Ask yourself which person is more valuable to have in your life. Keep in mind, true friendship trumps sexual chemistry. Or it should, anyway. Think with your head on this one, not your nether regions.
If she’s against you dating her ex, and you decide to regardless, you’ve already weighed out the pluses and minuses. You’ve already made the decision her ex is more valuable to have in your life than she is. You’ve already decided to risk losing her as a friend. Sounds harsh, but it may be the healthiest choice.
Oh, and don’t keep it a secret, she’s going to find out. Would you rather have her hear it from you? Or through the gossip mill? Be kind, be honest, be open, be real.