Would you contact a relative to make corrections about your family history?

I was on Ancestry.com and one of those leaf-thingy’s popped up.
It was connected to someone else’s family tree.
My great grandfather left my great grandmother and two sons in Italy… came to the US and started a whole other family.

This person has my great grandfather listed as “married” to the woman with whom he started this whole other family. (they had five more sons)

A) My great-grandfather and this woman were never married
B) My grandfather is listed on this persons’ tree, but this woman is listed as his mother
C) My grandfather’s brother is no where to be found, but the five half brothers are all listed

I am guessing that this person got the same “leaf thing” that I did, showing that we have the same paternal great grandfather. Should I contact him/her to explain the family history? Or should I just let it go?
I am hesitant to discuss this with my Dad, because I know it’s a sore subject for him. His grandmother eventually came to the US and lived with my Dad’s family until she passed. She was looked down upon as if she never should have came to the US since her husband “moved on”.