I'm going to stop being friends with someone who supported another person that ruined my professional reputation and broke my heart.
Are you going to do it in person?
I feel uncomfortable saying it face-to-face.
It can be awkward to be caught in the middle of two friends, but when one friend is blatantly in the wrong then you need to side with the aggrieved party. If you choose to remain friends with someone who hurt one of your other friends, then you'll be siding with a bad person and you'll ruin your other friendship.
That's fine since the guy I'm supporting is cool and they aren't.
I hope everything works out with you.