Over 25 million Italians have emigrated between 1861 and 1960 with a migration boom between 1871 and 1915 when over 13,5 million emigrants left the country for European and overseas destinations.
I'm in exactly the same situation as Vittorio!! I don't know about you Vittorio but in my case It's a sensitive subject with my mom - and NJ is a difficult state to obtain a copy of a divorce decree. Everything else is fairly simple. That one document however is difficult!!
I agree that you should ignore the divorce. Actually, it is your responsibility to submit only the documents that pertain to your application, and you have no obligation to -nor should you-- submit records that affect only your parents. Should they apply, it would be their responsibility to do so. Best of luck.