How to distance yourself from popular person without causing drama?

TW - self harm

Let's say r who is impulsive or compulsive liar, she have a friend in her school who basically knows the whole, very popular, conversationalist and good at using people

R doesn't like her anymore and her current boyfriend like her friend before

R does self harm, and she is 15 or 16, I'm 27, but idk how to help, i couldn't encourage therapy enough as our family is against it, her father doesn't know about self harm and lying tho her mother does

R says she can't break contact with her friend even tho she doesn't like her anymore

Her boyfriend is freaking useless too but she is anxiously attached

I know this is above reddit pay grade but how someone can distance oneself from popular person without offending them and letting everyone know

Edit - what are these replies, like if r could just stop talking and it will be done, then I'll not be typing this