I read these entries and my heart breaks for you as I know how much broken trust can hurt.
I see you make mention of wanting to hurt him as he's hurt you and these are completely normal reactions that I hope you continue to explore.
Am I worried about you? Not really b/c I know you too well now. You will do the right thing for yourself, your kids, and amazingly enough by him. He doesn't deserve how you'll end up treating him, but you will treat him correctly b/c that is who you are.
I'm glad you have decided to stop digging and torturing yourself. The only thing that can come from that is more pain for you. You know the sordid details, so learning more is just putting salt on the wound.
Take the time now to process all your emotions. Kerry is so very right that you'll unfortunately need to accept things about stbx's "new life" and how it involves the kids just like he'll have to accept yours.
He is a miserable man...maybe not even a real man, but still a boy. His actions were dispicable and immature. He exposed your son to his world of deciet and it would be understandable to never forgive him for that.
However, you will, in time, because you know that is the only way that you can be free. You know that you'll be forgiving him for Kalni, not for him. Forgiveness is about you, not the one you're "forgiving" - we could all give two real shits about the ones we're supposed to "forgive."
But, we need to forgive so we can live in the moment and plan for the future w/out being railroaded by the past. I'm working hard on this myself and I know it is an uneasy road, but in the end, we will always love the person we were with, but we won't be "in love w/them."
You'll end up truly hoping for his happiness b/c you know that is the only way he can really step up and be a good father to your children. That is your ultimate wish and you will be there someday.
...but not now. The time now is not to move forward, but to process the events of now. Take your time. Be angry. Cry. Yell. Scream. Destroy inanimate objects. Do whatever needs to be done. Process it all. Every last drop.