First, I would advise him to get a good lawyer and start protecting his assets. When the shock wears off, (ex-) honey bunch is going to come after him with all claws extended, painted Jungle Red and can make his life hell.

At 50, he probably would not be a good fit in the party scene, especially for someone new to it. If he is in a good size city, there are all kinds of gay groups that would be more accepting and a less threatening way to meet new people. There are gay bowling leagues, gay tennis leagues (or sports of any kind, for that matter), gay antique car clubs, gay glee clubs etc.

Good luck to your friend.