yes it is true. Near the end of the book the 11yr olds are leaving the sewer where they fought IT and they got lost. Bev decided that the way to regain their 'connection' was for all the boys to have sex with her individually. It worked and they got home after that.

Like I said in the books it is even more obvious that SK is a pedo than the movies cause there are things he can do in books you can't do in movies.