I think even with FERPA and an 18+ year old, the schools do have latitude (and probably willingness) to share information with parents in academic dismissal cases. See https://www2.ed.gov/policy/gen/guid/fpco/brochures/parents.html
I would imagine a child in this situation is withdrawn, ashamed, possibly even in crisis. This is precisely the time the parent needs to take the reins. Sitting out in the hallway is not supporting your child, IMO.
As I say, I hope and expect this situation can have a happy outcome in time, but it will take work.