Compared to the last few letters, this is a long one.
The major news: Craig and Sam have broken up. Of course, Charlie has a lot to say about this.
Long story short, Craig had been cheating on Sam. A lot. Mary Elizabeth's boyfriend, Peter, knew about it, and convinced him to tell Sam.
Charlie writes that he "wasn't happy about Craig and Sam breaking up. Not at all" (4.12.31). Really, Charlie? Really?
He then describes lunch at Bill's house, where he meets Bill's hippie girlfriend for the first time. They listen to music and eat salad and spaghetti, and during lunch they have a couple of very special moments.
Bill tells Charlie that he's "very special" (4.12.53) and that he considers Charlie a friend. Apparently the feeling is mutual because Charlie says that Bill is "the best teacher [he] ever had" (4.12.57).
Before wrapping up the letter, Charlie writes that the last person to call him special was his Aunt Helen. But he thinks, "everyone is special in their own way" (4.12.62). Maybe Charlie could get a job on Sesame Street.