Google: definitions of empire
Pick any definition you like and show me where the USA fits the description. Having almost 1,000 military bases in foreign nations that don't answer to us nor obey our rule does not make us an empire.
And what is so foul about our form of government that no one outside the US should be subjected to it? It works pretty well here, if you ask me. And anything is better than the dictatorships that ruled Afghanistan and Iraq.