I’m sorry you feel hurt, but I hope you will never again send someone else to do your dirty work. If you want to break up with someone, do it yourself. Say to the boy, preferably in person, “I like you, but I think we’re better as friends. I’m sorry.…” That’s common courtesy and, besides, the message can get mangled if you send someone else to deliver it. You should speak directly to your friend, too. Say, for instance, “I realize now that I shouldn’t have asked you to break up with him for me, but it also wasn’t thoughtful of you to hook up with him so soon.”