Honey, it's natural for things to hurt. You are human, he is your h of many years.
But, let me ask you something. Why do you know what he said to his sis in an email. Please tell her that you would rather not know what they are writing to each other. It doesnt do anything for you except set you back.
And don't project what you think are his feelings or lack of feelings. They are his and you have no idea what they are.
I know you think that you will never be able to do this. But, you will.
Detaching means that while you still love your h and are still standing, you are continuing to live your life without regarding to what he's doing. It means that you are loving from a distance. It means that you are becoming the person you were meant to be, for you.
Now, get back to your life, sweetie. Walk your journey. Let him walk his.
Here is a good article on detachment. I hope it helps.
