Co-parenting relationships

Hey

Does anyone else have a co-parenting relationship?

I have one which is very recent when my little one was about 6 months old

My main struggle is around the other parents attitude towards money, inconsistency and overall view that the child fits into their life and not them fitting into the childs life

I am trying at all times to be patient , not lose the cool and keep things amicable but i just feel im being mugged off and fighting a losing battle where things are just turned and onous shifts

Anyone with any tips as my ultimate goal is to be as amicable as possible and everything to be about the child but even i feel now my niceness and patience is being pushed to its limits