Emergency custody issues!!

My husband and his childs mother have joint legal/physical custody. After a dispute about school, my husband placed his son in our school district because he has tie breaking authority on academic issues. When the mother found out she filed for emergency custody and was granted based on false statements she made to the judge and the fact that my husband could not be there to contest her statements (he was training out of town for work). He was given less than 24 hr notice she was going to file and she is now not allowing us to see the child. My husband and I have been in court with her for well over 5 years and it has been exhausting, if she doesn't get her way she uses the court system to try to get her way. My husband wants to get full custody based on the fact his son is not doing well in school (in his mothers custody from Tue to Friday) and the fact that she us completely unwilling to put the childs best interests before her own. Please help!!