The Court can grant a Personal Protection Order if he has threatened you or the kids, or has been violent with you or the kids. Exclusive Occupancy Orders are great but they can take a long time to obtain, and can saddle you with mortgage payments, insurance, yaxes, etc..
In Michigan, a GAL represents the best interests of the minor child, and therefore isn't the child's lawyer. So the e-mails could be shared IF their disclosure furthered issues the GAL felt needed to be disclosed to advocate for the child's best interest. You could ask the Court to appoint you your own attorney in addition to the GAL.