I thought about your post for awhile, 'cause I wanted to give a thoughtful reply.
In the end, I'm going to paraphrase the 12 step literature: when I'm disturbed about anything, it is because I haven't accepted life as life is.
Acceptance and detachment, I think are the only two answers. Too bad we can't just snap our fingers and be accepting and detached.
For me, I have a strong sense of justice, and it wouldn't seem "fair" to me that I am expected to be friendly to H while he is seeing OW. So in my case, I am not accepting that I can't control H. I'm also not accepting that my choices to be kind and civil are for ME, not for others or their reactions. I don't know if that made sense, but it seems applicable to your sitch in my screwy mind.
Yuck, I sound like a sermon. But, I believe it.
So, IOW, the choice to be kind is a choice for nicola to be her best self. It really doesn't have that much to do with H, and nothing to do with OW, I don't think.
So at least I gave you something to laugh at!
I'll bet you heard exactly what you needed to hear at church. That happens so often.
