Does a father have the right to hide a health care provider from the mother when the child is under joint legal custody?

As a mom, I just learned my 14 year old son has been in therapy for 5 months (during a probate filing) without my knowledge or involvement in selecting a health care provider. When I visited the therapist, it was learned father failed to provide any contact information for mom and mother is not referenced in computer file at all as someone to call etc. We have joint legal custody. Child kept it secret to avoid family conflict as we just ended a custody battle dad initiated and lost. Father also lied to therapist and said he had sole physical custody which he does not. Father intends to call therapist as a witness in another anticipated custody battle. GAL already determined shared legal and sole physical to mother with 50/50 visitation by father a year ago.