I say do nothing. Your parents are both grownups. They can figure this **** out for themselves. BTW, what can you do? Talk it out? Your dad's behavior won't change if you talked to him. Your mom will not want to have this conversation with you. Likely, she knows what is going on. I do not know how but ... Women always do.
This. And you may need to mentally prepare yourself...your parents may not choose to live the way you want them to. And that's their right.
I'm going to go against the grain here and say you should tell your Mom immediately. If she is already aware/they have an open relationship, no harm done. If he is keeping it a secret from her, then you would be right to bring it to her attention. If he didn't want his affair to be exposed, he shouldn't have had it in the first place. Cheaters are scum. Had I been old enough to be aware of my own father's infidelity, I would hope that I would have exposed him.
This is probably the worst possible advice. It is very possible that your mother knows or at the minimum is aware of the possibility. The worst thing you can do is shame her by bringing it to her attention.
But, what if she is somewhere between knowing and not knowing? She suspects or assumes and tacitly allows but has no particular knowledge. Confronting her with specific information can catalyze a family drama without leaving anyone better off in the end. He could end up humiliating his mother because she would know that their son knows about it. If my wife was cheating on me, I think the last person I want telling me about it is my children. At least get your bearings as to which category she's in before going to the nuclear option.
Need more facts, the OP left out too many details. The part that I have a hard time wrapping my head around is the 17 years of being apart. I think there is more to this story......
Seduce the young gold digger yourself. She breaks up with your dad and you get laid. Problem solved and then some.
Speaking from personal experience, my mother didn't know. When she eventually found out on her own, she learned that her parents knew but didn't tell her for similar reasons to what has been posted here. That was devastating to her. My aunt was also unaware that her husband was cheating on her. She found out when one of the woman her husband was cheating with confessed to get back at him for cheating on HER with another woman. At no point were they better off not being told.
Cool, A. I always edit my posts b e c a u s e I t h i n k s l ow. and thoughts just flesh out over time.....one reason not to act impulsively. and B. yeah, we we really saying the same thing. As an old fart, I strive to be a voice of reason because 'life is hard enough' and maybe I have learned something that can help The Kids, if I can do it from this chair and not have to actually get involved. I specifically avoid douchiness.......except in the D&D where I will hammer stupidity in a douche like fashion.
I can appreciate that. But, were these women who lived away from their husbands for 17 years? I think telling Mom might be a good idea depending on the situation -- if she really is oblivious (or suspicious) and the infidelity is really an out-and-out transgression of their relationship. But, if she already knows or accepts, I don't think it's so wise. Like in all things, I think the OP should inform himself before acting.
If she already knows, then the only thing revealed would be that her child also knows. I suppose an anonymous letter could be employed to avoid that, but to me it just seems that oblivious mother not being told is a far worse outcome than aware mother being told.