Breaking up with someone can end in a disaster, but finding out that someone you know is hooking up with your ex can lead to even worse problems. Be forward and ask how long the relationship has been going on. You can warn the person to be careful if you know your ex has issues, or you can encourage them and let them find out on their own why you two broke up in the first place. For those cases where you are not happy about the relationship go ahead and let them know by yelling, or firmly telling them.
