I've been struggling with regret lately, too. But I've come to terms with it. She is as much at fault for our marital stress as I was. She is the one that cheated. In my case she wanted out. An exit affair. If she would've served me papers she knew I would have fought her tooth and nail. Counseling. Therapy. SHE ALONE chose the one act that she knew I couldn't overlook or forgive. Whether she did it consciously or not she knew I can't come back from this, not to her. SHE ALONE chose to suffer in silence, to pretend. To not share her feelings, boredom, restlessness.
I truly hope my STBX has a great life. She won't . She's broken I see that now.
I can't help that, not anymore. I've chosen to be a better person. Happier. More outgoing. I don't sweat the bullshit anymore. I'm closer to my friends, my family and to God than I've ever been. My actions in our M were honorable and mt intentions were pure. I now know that I couldn't ever be responsible for her happiness.
Gently, my friend, regret is a wasted emotion. It implies a transgression. Chances are that given the same circumstances, stresses and timing you would react the same way if somehow you had the opportunity to 'do it all over'. It's just you being you.
I wish you strength. Take the regret and use it to be a better person. A better parent. Her life is no longer your concern.