Hello! My boyfriend (US citizen) and I (non-us citizen) are going to apply for a K-1 fiancee visa. My fiance got separated in January 2014 but got a divorce only in November 2015. We've been communicating since July 2014, but actually met only in July 2015 and have been together ever since (we spent 1 month travelling in Europe and then we lived on the Caribbean for 5 months together, because he was studying there).
We wrote a story of how we met as a supplement for the petition (point 34.a) (signed and dated by me and my fiance). We also wrote a letter as the intention to get married (signed and dated) within 90 days upon my arrival to the US. We have enormous amount of pictures together/with friends/screens of conversations, 2 affidavits from his friends, confirming that our relationship is real (we can get more) etc.
1) Do we need to mention somewhere (ex. "Intention to get married", "Supplement for point 34.a", Affidavits from his friends) that all this time he has been separated and his wife knew about us (our pictures are all over FB) or the USCIS can put two and two together?
2) Can our petition get denied because of that?
3) He is going to visit me soon, so he has an official invitation from my country and a visa. Do we need to include it in our package too?
Hope to get some answers!
Thank you very much!

