If I homeshare on my boyfriends xbox can he then homeshare on his friends xbox and then they both get my games? I haven't tried to do it because I don't want to mess anything up until I know for sure.
No they won't both get your games. Your boyfriend will be able to play your games on his console as it is your home console. They can't access your games from their profile on any other console, even if it is their home console.
Your game licenses are bound to your profile (and move with the profile) meaning that you will have access to your games wherever you (or your profile really) is. The licenses are also bound to your home console and whichever profile is signed onto that console can access your content.