What type of evidence can be used in a child custody case to prove my ex is an unfit mother?
While I am not licensed to practice law in your state, I can give some general guidance on this issue.
Assuming that your state is similar to New Jersey, where I practice, if an agreement cannot be reached between the parties, determination of legal and physical custody, as well as parenting time (visitation) rights will ultimately be up to a judge.
It is extremely important that you speak with an experienced family law attorney in your area in order to prepare and present the best possible case. Proving that a parent is unfit is an extremely difficult standard to meet, and may not even be necessary in order for you to have primary custody of your children.
Your attorney can discuss all of the options with you and ensure that the case is presented most effectively.