If a child complains about the other parent or the other parent's household, encourage them to discuss it with the other parent and let them know you are confident in their ability to work it out with the other parent. Mom really loves you. I think you need to let her know this is bothering you. I'm confident that you two can work this out together. Help your child have love and respect for both parents.
Parenthood lasts a lifetime.
Act responsibly so children are secure in knowing a responsible adult is taking care of them. Another thing to remember is not to give children the responsibilities which belong to a parent. An example of this is leaving the determination of the time sharing schedule to a child. This puts the child in an awkward position. For one thing, it is too much responsibility for a child.