Yes, I think I know that song. "They may not be together, but they still love me" or something like that. She never said they were divorced indeed - she just sang about her parents living in different trees.
I think that was a great way to deal with divorce - just explaining what it's about to have "two homes", and not the whole "daddy and mommy don't love eachother anymore" thing. That would only confuse kids.
I remember Guy Smiley's final performance. A barber was going to cut this guy's hair. Until Guy burst through the wall in a white tuxedo and started singing a song about air while a marching band came in as well. And everytime the barber said a word that rhymed with air, Guy would bust through another wall and sing about air again.
And I believe I've seen Jim's last performance of Kermit was when he and Miss. Piggy were on a talk show, (I can't remember the name) talking about the Muppets at Disneyworld. When the host brought up something about Piggy getting stuck in the cement at the Chinese Theater there, she threw a tantrum.
Long ago, sample pages for the Sesame Street 40th anniversary book were posted online, and by the time the book was released a number of changes had occurred. One thing that appeared in the sample pages but not the final released version was a section on Jim Henson's last day on the Sesame Street set, which said that his last segments were Kermit's "I Wonder About the World Above Up There", Ernie's "Don't Throw That Trash on the Ground", and Sesame Street News: The Bird Family. And I noticed all three of those segments used park sets.
I wish that the 40th anniversary DVD included some of Jim Henson's season 21 segments, whether they were from his last day or not. Too bad no such segments were included.