I am glad that it seems to have worked out.
But, I think it is just a lucky situation.
And, I stand by every word in my earlier post.
If this OP continues to be personally and vicariously involved with her teenagers life.... then there are gonna be HUGE issues.
Really, it is not like these are two girls, BFF, having a tiff.
And, even if it were, the OP handled it ALL WRONG.
A teen should NOT have her relationships controlled by her mother and her mothers 'family friendships'.
Instead of sending kudo's.... I am sending a strong message that that the OP got lucky THIS time. And, that one day, very soon, if her DD is smart, she will refrain from telling her mother ANYTHING about her life and her relationships, and as she becomes 'of age', she will be running for her life, away from her mother's overinvolved, wayyyy to vested, vicarious, meddling, and disrespectful ways.
There is a huge difference between being there for your child, giving advice, maintaining strong boundaries, discipline, etc.. and behaving as the OP has done.
Beginning with how the whole relationship between two barely-out-of-their-14th- year 'family friends' was handled in the very beginning.