Genealogy Chat

Would really appreciate some advice on the following (bear with me if the text bunches up! :)): My father was adopted in 1944 (a war baby). His dad was an American soldier, his mum from London. I am now helping him to find out more about them and their families. My search has been slow and painful so far. I have found my dad's real father in South Carolina (he died in 2001). Through ancestry.com I've found out my dad has 2 half brothers, 2 aunts and a plethora of nieces and nephews. Even found a 3rd cousin in the UK. All in the space of a few hours! The problem is that it appeared that he was married at the time of the affair, and from my web searches, his wife is still alive. How an earth do you go about contacting these people? Is it worth it? Or would you just be upsetting everyone unnecessarily? Should we just wait until the wife has died and then get in touch so that we wouldn't be causing her too much or try and contact another wing of the family to try and establish who, if anyone, knew about my dad. His father gave his name on the birth certificate and a very distinctive middle name that links directly with the family, so obviously cared. Does anyone have any experience or advice for this type of scenario and how best to contact people that may not know of your existence? Would be v grateful. x