My point of view from the child's perspective...

I'm 2nd oldest of 5, mum and dad divorced when i was 15, youngest was 5. Oldest was out of home. 2 next stayed with mum (and then stepdad) and 2 young ones stayed with dad.

Dad constantly complained how mum ripped him off, cheated blah blah blah. Only that my sister and i knew what had happened we made up our own mind. The 2 littlies had to wait for that day

11 years later 4 out of 5 children speak to dad but don't have a great relationship with him. At the end of the day while my mum didn't whinge about paying for us, driving us places, feeding/clothing/schooling all these other things that add up (and c/s is a mere drop in the ocean realistically) the 2 younger ones chose to move in with mum and step dad.
While my step dad worked and made a living mum was an at home mum for us kids. So maybe he paid more than his 'fair share' but he certainly has received a lot more love and respect and a real relationship from his (step)kids, He even walked my sister down the aisle at her wedding!

I do believe kids grow up to look at things through their own eyes and see things for what they are. I know the $$ is a tough issue at the time but I think when your kids are adults and you're not still paying for them, it's not who paid most % that counts.

Having said that i certainly don't think you're being unreasonable, I just believe you will 'win' in the end no matter what!
Good luck