We're supposedly 'best friends,' but we wont admit we hate each other?

I've entirely checked out on my part of my friendship with a girl named Samantha, because she's a horrible person in my point of view, and for a while, I hated her, and wished for the worst for her. I already know that was horrible of me, and I did let it go. She wont check out of her part of the friendship, because she doesn't want to confront me or be confronted, and we also have a mutual friend that we both call a best friend, and we don't want to drag her into the drama. I can't say that I really hate her, it's more like I know her ways, and I entirely disapprove of them, and I think she needs to be put in her place. Other than back out slowly, what do I do?