Think about this.

You catch your mother cheating on your father, they've been married for a little over 20 years and you're about 20.

What would you do?

This really all depends on wheather or not you have siblings who is of an age where this might affect them. If you have then is it worth all of the agrovation and possible breakdown of their familar unit?

So what he doesn't know won't hurt him.

P.S Don't get drunk and splurt it out like some kind of soap opera reveal. Its so cliche.

Confront the madre and say plainly "Hey, I know you're cheating on dad." Whatever else you think you need to say. If it was me I'd say "I know you're cheating, and either knock it the fuck off, get divorced, or make sure I don't know about it.Also, fess up or I'm spilling the beans." I'd probably then move out of the house because I don't think i could stay living in the same place as my mom if she were cheating on my dad and I knew about it.

No matter what though, shitty situation. Hope things get better. :(

My sisters are both in high school.
It's been bothering me all day. I keep jumping back and forth between wanting to tell my dad and not wanting to. I don't want her to fuck my family up. It makes me so angry. :(

tell her you know whuddup. put it in her hands. sorry to hear matey. how young are the high school kids? :| not sifty, just curious as to mental maturity there...

Your avatar is too perfect for this. Ferox summed it up pretty good I thought.

Did she see you see here? Because if yes, hopefully her guilt will solve her problem for you.

That's tough. I actually did catch my dad cheating on my mom in our house (on my 19th bday) great way to wake up that morning.

I grabbed the bitch he was with, told him he was a piece of shit, packed a bag and called my mom and told her at work. Prolly not the best place I should have told her but I was so furious and disgusted that I didnt care. I dont recommend you doing the same though cause I felt pretty bad about it.

My brother was already married and moved out and I was 19 and engaged so I didnt have any sibilings to worry about. I do think your dad has a right to know.

Talk to your mom first though. Give her the opportunity to tell him herself or to maybe stop it. If she doesnt, or doesnt seem to care, then I would prolly say something to your dad. Your sisters are in high school, they will be able to handle it. No one likes a broken marriage but whats the difference if your parents are divorced or staying together and you knowing the whole time that your parents marriage is crap because of the cheating?

nothing.

So far, that's what I've done. lol

All you can really do is confront your mother. I mean, if you parents get divorced at their age all it means is they are going to be wasting all the money that they have remaining/saved up.

Then again, she may be doing that right now anyway. . .

Video camera.
Upload to whatever.
???
You now have money to pay for your Dad's lawyer.

That's exactly what happened to me. Except it was 19 years.