when friends divorce

Friends of mine are getting divorced. It is a messy, angry, bitter, hostile, greedy situation. It feels awful watching them disintegrate. i like them both. I am trying to not take sides...I would like to remain friendly with both of them. Yesterday, she told me that I cannot stay neutral. I must choose between them. I'm not sure I can do that. Am I wrong? What can I say to make her understand?