Wanting to maintain a healthy relationship with the other parent is wonderful and crucial. Do not be a pushover to make it happen.
Your children need you just as much as the other parent, so don’t let your role be diminished in an attempt to please someone else. There’s a fine line to walk to accomplish this, but it’s your duty to be there for them. Even if that means upsetting the other parent. Be sure to be well represented through the custody discussions and fight for yourself because your kiddos need you to.
Value your role more than your relationship with another parent. Do it with respect and kindness, and lead with your love for your children.