Mine decided to tell us separately, so mum told my elder two siblings whilst collecting them from school and dad told me and twin. Not great.
They proceeded to go to court for the next 16 years. Fucked up.
Contact time was totally rigid. Down to the last millisecond. Not good.
Dad still, despite being married to another woman (one of the three affairs he had that I discovered as an adult) bangs on about "what mum did wrong" - totally shit.
Dad paid fuck all in maintenance, nada. - again totally shit.
It was an harrowing experience, if I'm honest. As for how I'd change it if I could, I guess I would ask them to be adult about it, and the children should know nothing about the ins and outs of things.
FWIW I separated from my children's dad when they were 4 and 2. He's a dick, but my children will find that out in their own time, they'll never hear it from me.
Best of luck with everything.