Having gone through an ugly family breakup, I can attest to how painful and stressful it is for everyone. Especially once the courts get involved.
From my experience the courts are very unsympathetic to any arguments outside the general consensus, almost to the point of being obtuse or jaded.
I know people think that children are better off having both parents involved in their lives but I beg to differ when selfish vendictictive parents are involved.
Childhood is important but it is not a lifetime, in some ways it is better to check ones ego and just step back and wait. Support the child as ordered by the courts and then when the child is an adult they can decide whether or not to have a relationship with the estranged parent. If they choose not to.. Accept that and live your best life, after all You don't own the child. (eventhough your ex may believe they do!)
This can be much easier on the child than witnessing constant bickering, accusations and pettiness between the parents. Possibly resulting in self harm or violence.
Just my point of view, might be wrong but nevertheless how I see it.