If thats the case than I can assume this guy is about the same age. I would tell your bf now in case this other guy decides to be immature and tell him first. He may not be too happy about your flat out public rejection (there was nothing wrong with your reaction though) and try to convince your boyfriend that you are the one at fault.
Keeping this a secret seems sort of incriminating for you so I'd just tell him.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.