Generally, in a mediation, in a family law case, the parties will attend mediation and be in one room for a brief period of time for the mediator to provide the rules of the game, how the mediation is going to occur, what the confidentiality components are, and the like.
After, most of the time, mediators will divide the parties into separate rooms, and the mediator will move between the two rooms to facilitate an agreement between the parties. However, that is not required. It is possible that you would be in one room during the mediation process, but generally, the parties are in separate rooms and the mediator goes between the two parties.