Summarize this article:

Take your friend aside and tell them that you need to talk about something that is important to you. Explain how it made you feel to see or hear others talking about you. If it feels like your friend isn't listening, try to stay calm. You won't make any headway if you start fighting during your talk.  Only confront your friend if you are certain they have been talking about you—don't just go on someone else's word. It's no fun to be falsely accused, and you may lose a friend if they haven't done anything wrong. Avoid getting into a back-and-forth. Try to keep the conversation focused on the fact that gossiping is hurtful and wrong. Your friend may feel defensive or have reasons that they think justify gossiping, but there is no excuse. Be firm about the fact that you do not like participating in gossip or hearing it about yourself. Tell them that they hurt your feelings and that you're concerned about the friendship. For example, perhaps you told your friend something private about your family, and they shared it with others. Say something like, “As your friend, I want to be able to vent to you about my family and trust that you’ll keep it between us. Just because I tell you something doesn’t give you the right to tell other people about it.” If you're really hurt by being gossiped about, you may want some space, or a genuine apology. Be honest and tell your friend what (if anything) they can do to regain your trust.  Let them know that you value honesty and loyalty in a friend. Make it clear that if they can’t uphold these values, you won’t be able to continue the friendship. Be specific about what you expect from them. For example, say, “If I share something personal with you, I expect you to keep that between you and me. If other people want to know something about me, they can ask me themselves. I’ll do the same for you.”

Summary:
Find a private place to talk. Express your concerns. Tell your friend what you need from them.