Family dynamics vary so much...
I can't relate to your particular issue as an adult, as I have no kids. However, my parents' divorce was finalized shortly after my 18th birthday.
When I was a kid, they separated for a time, my father moved out. I still don't understand the details, however, from the little I do know it wasn't an affair, basically he wanted to room up with a bunch of friends, have parties, and so on, and my mother didn't want that environment for me and my sister, so they separated. I was about 6 years old. When I was about 10 they tried to R, bought a house together in a new neighborhood. By the time I was about 13 they were sleeping in separate rooms.
For me, the damage was done with the initial separation. When my father moved back in, I no longer viewed him as my father, and he held no authority over me. I rebelled against my mother as many teenagers do, but I still respected her as my parent. I blatantly disobeyed my father on the rare occasion he tried to tell me what to do.
He moved out when I was about 16, my ultimately sister "chose" him a few years later and I chose my mom. I didn't speak to him or my sister for about four years. When my husband and I were planning our wedding, he practically had to force me to R with my sister, but it was a good thing, 12 years later we're best of friends again.
Ah, but my mom... I worried about her when I was a kid. I respect the decision she made to not want to expose my sister and I to custody issues, to having to say our parents were divorced when we were children. She didn't even date for a few years after the divorce. The past is the past, she finally did start dating, and she met a new man who is committed to her and their relationship, and she remarried about 5 years ago. I don't view him as my stepdad, I'm 35, but he has been more of a father to me than my dad was since after he left when I was 6.
I'm glad that she is happy now, with a quality male, but I look back on that sacrifice that she made, so many years without a true companion, for the sake of me and my sister. I am grateful for the love that she always has shown us, and continues to show us. But, I looking back on it, I would have preferred her to seek happiness for all those years. I would not have respected her less or been less grateful for her had she chosen a different path. I want her to be happy, and I feel that she genuinely is happy, but I don't feel it was necessary for her to have delayed her search for it for my sake.
My mom is fit and healthy, physically and mentally, educated, smart, and attracted a quality male with similar qualities. My father is obese, smokes, does pot, is still alone. The last time I saw him (at my sister's wedding) he got high, suggested I get high with him, and then accused me of deferring to my smothering mother when I declined (I had moved out of state and staying with her and her new husband for the wedding events), and then followed me out to my car, tried to not let me get in, drunk and high, blabbering about how he loves me and my mom. I'm going to assume that your husband is a better father than my father is. I send him a happy birthday text once a year if I manage to remember.
Anyway she did what she thought was best for us, I just wonder if it was necessary, and if it was best for her as well. If she had divorced my father and dated before I turned 18, I am confident that she would have formulated an appropriate way to handle it, and she wouldn't have had to give up years of potential happiness. Then again, she also wouldn't have found her new husband, but hey, who can predict these things? I think everything turned out ok for her, but look, life is so short. Can you do right by your kids without having to sacrifice years of your own happiness?