The correct spelling of "hadst gettogether" is actually "had'st get-together". The apostrophe marks the omitted letters, and the hyphen indicates that "get" and "together" should be considered a single compound word. In IPA, the pronunciation would be /hædst ɡɛt-tʊˈɡɛðər/. This is a less common construction in modern English, as we would more likely say "did you have a get-together?" or "did you get together?" instead of "had'st get-together?"