when this happened to me I told my best friends that I'm back with him, they weren't happy about it and they don't all need to ever interact, but one of my best friends (who's now just a friend, because we've lived and grown apart) told me that as long as I'm happy, she'll be happy for me and it's all that matters. If I'm having any problems with my boyfriend, I won't make that mistake of telling my best friends again to turn them against him. I'll confront my boyfriend. I lost my other best friend, but it wasn't meant to be, especially because I was the one making any effort.
Be honest with your friends, if they know you're happy with your decision, they'll be happy for you. And I can only recommend not trash talking the relationship with best freinds, I mean what can they answer? "then break up already"? I learned that it's never good to talk to people you're close with about your private relationship problems.