Characterising someone's politics as Stalinist or Stalinoid is "insulting"? Okay - fine; but no-one has a "right" not to be insulted or offended by someone's criticisms of their politics. If you think Cathy's assessment is wrong, argue against it politically - don't just demagogically invoke your wife's family history and complain about how "insulted" you are in order to deflect the criticism.
Sharp polemic requires you to call things by their proper names. If we think someone's politics are Stalinist - or influenced by Stalinism (that is, "Stalinoid") - then we say so. It's called being honest.
Try it sometime.