You are a kid you need to be a kid do not get involved in adult things.. It is not for you to get in the middle you should not know about anything your mom does and you should not try to stop it. Furthermore you should not be the one to tell your dad.
Tell your Mom that you know she's cheating on your Dad. Tell her that you think she and your Dad should get divorced, and that after the divorce, you want to live with your Dad. Tell her that you never want to see her again, because you're mad at her for breaking up the family.
Now, much of that might not be true. But say it anyway, because it'll be a wakeup call for your Mom. It'll cause her to change her mind, and not cheat on your Dad.
In which case they won't have to get divorced. And when she says she won't cheat, then you should tell her to stop going to that gym too. Note that it sounds like your Mom hasn't cheated yet.
But tell her that you know she is cheating. Present tense. Say it like she's already started cheating, and you know it.
That's not true, but saying it that way will help justify all the other things you say, like how you never want to see her again.
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.