“Her having sex after we broke up isn’t the problem. Her having sex whilst pregnant with my child, is the problem. It’s undoable.”

I don’t understand what you mean by ‘undoable’. Do you mean she shouldn’t have done it? Or that it can’t be undone? What? What’s the problem with it?

“It affected me so much that I had to move 50 miles away. I view the men she had sex with whilst carrying my child as fateful enemies & wish they be held accountable for their actions.”

But those dudes did nothing wrong. Accountable for what actions? Having sex with someone who wanted to have sex with them?

“If I hadn’t moved away I would most likely have administered punishment myself. Poetic justice would be for them to experience exactly what I did. For the woman carrying their child to screw around whilst pregnant. I do hope this to happen to all or any of them.”

Why would you assume those guys would even be upset by that? You act as if there is some kind of universally understood rule that you can’t have sex with a woman who is pregnant with a baby from somebody else, but there isn’t. Seriously. A lot of guys wouldn’t even care, even if they cared about the kid.

As for “rolling over” and accepting the facts of reality, I’ll leave you with this from the dhammapada (first chapter):

3. “He abused me, he struck me, he overpowered me, he robbed me.” Those who harbor such thoughts do not still their hatred.

4. “He abused me, he struck me, he overpowered me, he robbed me.” Those who do not harbor such thoughts still their hatred.

5. Hatred is never appeased by hatred in this world. By non-hatred alone is hatred appeased. This is a law eternal.

6. There are those who do not realize that one day we all must die. But those who do realize this settle their quarrels.