You handled that extremely well. You were upfront and honest with your kids, but also reassuring and loving. That is what they need. They don't want a tug of war. They need some consistency. I'm not sure I'd like the back and forth that a 50/50 involves but it is what it is. I think kids are resilient and can cope with things that they are clear about. Knowing the routine.
Judges don't like to make changes unless something CLEARLY is not working. It does not sound that way to me. If the kids were really unhappy around your fiancee and you - that would be different. But it seems it is Ex who is the unhappy one.
