[Hamish McBagpipe]

You will get plenty of opinions about your Dad's actions, I don't have much opinion on that.

But you sound pretty emotional about the prospect of your parents breaking up. My parents divorced when I was only a year or so older than you are now. This [censored] me up in a hundred different ways even though I knew they had had a pretty poor marriage for a number of years. It took me far too long, at a critical time in my life, to get over it. It isn't the end of the world and no matter what is going on between your parents you can not let it get you down as much as I can tell it would currently. I'm not that interested in what your Dad did. It's pretty clear to me, though, that you would be in a bad state if things deteriorated.

I have since forgiven both my parents for much worse sins than internet sex. But it took a long time. The fact that you have already communicated with your mom, I think, means you will hopefully still talk to them both if things get worse. Shutting them out is the wrong path, I know, no matter what happens. As well, marriage difficulties can [censored] up your relationship with your brothers/sisters. Don't let it.

Not much advice on actually how to stop issues between your parents [censored] your life up, sorry, but you'll have to find a way. Good luck.