Andy Cohen Sends Love and Condolences to Mary Cosby After Son's Death

Andy Cohen is reacting to Robert Cosby Jr.'s sudden death ... and he says his thoughts are with 'Real Housewives of Salt Lake City' star Mary Cosby.

The Bravo host spoke at length about Robert's death on his radio show ... revealing he's already had a long conversation with Mary.

Andy mentioned Robert's struggles with addiction and his legal issues ... and he said Robert's death at just 23 years old is every parent's worst nightmare.

We broke the story ... Robert died Monday in Utah ... and while the official cause of death is unclear, police responded to a report of a possible overdose and upon arrival it turned into a death investigation.

Andy says Robert was fortunate to have a loving mother like Mary, who did everything she could to help him with his addiction ... and he hopes their relationship, as we saw on reality TV, might help other families going through the same thing.