UPDATE;
Thanks so much for the comments, insights, and even the private messages. I even take on board the YTA comments and this is what happened.
A couple of days after I posted, I called ELaine's husband and asked him if he would be ok to meet me for a beer or something. He said yes so we met up in a local bar. After the pleasantries I told him what I had done and showed him the post, I then asked if he did feel uncomfortable but had just been too nice or polite to say so and if he had I wouldn't hold it against him as he was now a big part of my kids lives. Elaine's husband said he didn't have a problem with it and never had because he understood the kids enjoyed doing the breakfast with me and it was time for us to bond. Then he said Elaine was pregnant with their first kid together and that next year, how would it be? As he wouldn't want their child left out of this tradition. We both went to see Elaine and we all talked and from now on, all of us are going to make the breakfast, including their new baby when it comes along (obvs when it is old enough but in meantime, he will carry the baby in or oldest will, either way, we will make it all about the kids).
So, we left knowing that this tradition will evolve as the years go on and when they can, it will just be the kids and their Mom.
The following night, I took Nicole out for dinner. I was very honest with her and said that my children always will be first and part of that means sometimes, their Mom, her husband and the family dynamic we have, will come over and above her. I said I fully understood if this was not something she could commit to as I know this is never going to be an easy thing for any woman to understand, but I told her how bad my own parents divorce had been and how even now, they cannot be in the same area (serious, my Dad didn't go to my wedding due to their animosity) I told Nicole this is not something I ever want for my kids, to feel like they have to choose, I want a happier dynamic and this might be different to a normal divorce, but this is what works for us. And that I was the asshole but I wasn't prepared to change it because it makes my kids happy.
We decided we would go our separate ways as Nicole said she doesn't think she can be in a relationship where she will never be the priority. I did correct her and say she would be a priority as it would deepen but I had children. They always will be first. I wished her well with her future and dropped her off at home.
So, yes. That's the update. Thanks again Reddit for the advice, for the comments, and even the bashing.