<human>: Give me the gist of the text in a nutshell

About 3 months ago, my two best friends (whom we'll call Sophie and Lucy) got into a fight after Lucy told her boyfriend something personal which Sophie had told her previously in confidence, asking her explicitly not to tell anyone. While I am not certain since I don't know what Sophie told Lucy, I believe Lucy told her boyfriend because she was worried about Sophie. Naturally, Sophie is upset, but she now no longer wishes to be friends with Lucy and ignores her apologies and attempts to explain why she did what she did. Lucy admits her mistake and says she doesn't want to lose Sophie as a friend, but Sophie retorts that she should've thought of that before telling her boyfriends things he isn't supposed to hear. (It doesn't aid the matter that Sophie and Lucy's boyfriend REALLY don't get along).

The thing is, both of them are asking me for advice and are more or less pressuring into taking their side. While I can relate to both of their arguments I already told them that I value both of them equally and that this is something they have to deal with between themselves. However, I feel that things are destined to fail with this scenario and I keep telling myself I should mediate, but I don't want to risk upsetting one or both of them and losing them as friends.

I know both these girls for a long time and love them both dearly. We hung out as trio every chance we could get, and it pains me to see the friendship between those two fall to pieces.

 Maybe I also am this desperate due to egoistical reasons (I don't want this trio to break up because I just have the best times of my life when hanging out with both of them at the same time!), but I seriously care about these girls as if they were my own sisters. I want to support both of them and continue being friends with them, but how can I do that without the other one thinking I'm siding with her "enemy"? Is there anything I can do to save Lucy's and Sophie's friendship, or does it sound like it's over to you all?
<bot>: Two best friends are fighting and on the verge of dissolving their friendship, I as the third wheel don't know whether to help out or stay out.