Maintaining peace amongst difficult situations

I pray for the peace and protection of my friend who I believe his narcissist estranged spouse is sharing slandering things about him. It seems she’s done it to his good friends whom no longer talk to him and for me watching this is painful from them outside. I struggle with injustice and feel in my gut and a strong message from God that I know my own instincts are correct and that I should continue to support my friend no matter what.