At this point it truly no longer matters. The best you can do is to move on with a new life. It’s normal to mourn what you lost or thought you had, but after a reasonable time the future is your most important concern.

You are divorced. It is up to him who he sees.

Look at it this way: It sounds like he was going to be a ******** towards you regardless of whether you stayed married or not. Regardless of whether the divorce was amicable or not. You've now removed him from your life, and I'm assuming because of how you describe the divorce as amicable, it'll be very difficult for him/anyone to paint you as in any way at fault here. Go, enjoy your life free and clear of him.

From where I’m standing, I don’t think the coworker was the reason for your marriage ending. You are not together anymore so he owes you nothing. He found his own happiness and it has nothing to do with you. You may feel like he “betrayed” you - think what you want, but the truth is, he didn’t. The coworker is still someone “not to worry about.” He divorced you for “just not feeling it” or whatever other reason. Those reasons probably still stand. Removing her doesn’t put you back into play. He moved on, you should too.