Sweet girl...your H is broken. His actions clearly reflect that. YOU didn't break him. You can't fix him, either. You have been treated unfairly. View him with the knowledge that he is messed up. It helps with compassion, which leads to forgiveness.
As long as he is with OW, there is NOTHING you can do. Just drop the rope. Let him screw up his life. You protect yourself and your kids. Make YOU a priority. You are faithful, loyal, sweet, and extremely caring. That is a great start!
Believe me, I KNOW how much this hurts. Impossible to explain unless you've been there. But letting him go to make his own mistakes is so empowering. Focusing on yourself helps with distracting yourself from thinking about H. Both of these help you with being more positive.
You're a woman of faith. Ask Him to help you detach. I promise, it works! Just know I and many others care about you. We're here for you. You are not alone.