Ok, I'm not Italian, but have been learning for a number of years. I have always found that sposa = bride and moglie = wife and fidanzata = fiance or serious girlfriend. This is confirmed by my huge Collins dictionary. I am open to learning new usages, however: do you have links to any of those dictionaries?
thank you,Thoughtdiva, for the clarifications. Now I used a huge Webster's and learned that a bride is not only a woman about to be married but, also a woman newly married. I had visited only my small and old portuguese/italian dictionaries (edited before internet era rsrsrs)