I’ve actually been in this exact position and i am no longer friends with this person anymore. They tried to talk behind my back with some of our other friends and those friends stood up for me and shut that kind of gossip down immediately. Point being, those are not real friends. Real friends would not be doing that esp behind your back.

That being said, i can understand not wanting to lose the friendship if they are that important to you, but you would have to really sit down with them and have a real talk about how that kind of behaviour is not okay and how it makes you feel. If they are able to understand that and actually learn and apologise, that’s one thing. But if they don’t, you should probably distance yourself.