My mum and dad separated when I was about 8. They didnt get along, screamed and shouted at eachother around us, used us as weapons against each other, constantly shit talked each other to us which skewed our opinions on the other parent. We lived with our mum and were forced to visit dad even when we didn't want to.

Splitting up is fine, forcing yourselves to be together for the sake of the kid is more toxic than any split would ever be.

Get along, go out together (restaurants and such) with the kid, make sure you're parenting on the same level. Communicate. If you start to see your kids behaviour ls changing negatively, get a therapist. Be open about you and mum not getting along anymore and how it's completely normal but you don't love him any less. A united front is the best thing for the kid.

I imagine its gonna be very difficult but way worth it. Me and my siblings all have damage that goes back to the way we were raised after our parents split up.

Hopefully this helps.