Feeling betrayed by a friend

I feel betrayed by my husband from whom I am getting a divorce. I do not think he is a good person. I like or agree with my reasons for believing this.
What I feel is difficult for me right now is that a few friends are remaining friends with him, two of the three also remain friends with me, one does not.

I feel betrayed by my friends, all of whom were my friends before they were friends with him. When I don’t think about it, I am fine. I have enough friends. However whenever I think about it, or hear about them doing something together, I feel upset with my friend. I tell myself that I would never betray my friend by being friends with their husband, if their husband was behaving the way mine is.
I feel strongly about this. I’m not sure if it makes sense for me to talk with these friends or not.

So, I think my model is:
C: divorce, friends
T: this friend is not a true friend because they help/hang out with my ex
F: betrayed (is that a feeling? Maybe lonely or abandoned or let down???)
A: ruminate – how can they do this? I would not do that to them. What should I do about this? I’m not doing anything – I should speak up for myself/do something about this.
R: ??I’m not being a true friend to myself at these moments?

What would be the action – other than just not thinking about it/focusing on something else – that would bring about a result of not caring or being a true friend to myself… or maybe a true friend to them or to my other friends??? I’m trying to think what is available. . .