Breathe and cool off...wait 24 hours. In my stich there were plenty of friends and the OP telling my wife that she needed to move out, we were the problem, and even sending ads for apartments for rent. These are all things out of your control....so as much as it sucks to see it....it has to be let go.
Going to the gym....good way to remove yourself from a bad situation....Kudos!
As far as being treated like crud last night....How would you have handled it if the roles were reversed? Would old Eric complained to his friends at the gym? Would old Eric been confided in others? I am not making light of her actions....but sometimes the hardest mile to walk is in some else's shoes.