So, he had been dating this new woman for 15 years but only divorced your mother 12 years ago? How the hell did the other woman not care that he stayed with his wife the entire time they were dating?

Your parents not only are assholes, but idiots as well. They thought the divorce would mess you up? What about a whole life of lies?

Feel so bad 4u

"U - I would die 4 u Darling if u want me 2 U - I would die 4 u 2 3 4 u" Next up: "Purple Rain".

I think they didn't wanted to break ur heart, I mean u were a kid nd it is hard for kids sometimes

It sounds like they went to great lengths to protect you. I don't agree with what they did, but I am assuming they did the wrong thing for the right reasons.

WTF? How could they pull such a move for so long? Was your father still living with you? People do the dumbest things for their loved ones, thinking they are protecting them but in the end only making things worse. I can't believe they thought it would be a good idea. And I can't believe that your ma and your dad's girlfriend went along with this. FYL OP, if you're of age (meaning if you're independent), you should take some distance from your parents as a lesson to them. They need to understand that what they did is utterly wrong and stupid and in the end very cruel to you.

Screw your mom for spilling the beans! For 15 years, your mom, your dad AND the other woman have been OK with the charade just to protect you. They could have kept up the ruse until you left the house and pretended the swap took place recently. That is some truth you really didn't need to know.

If they've been keeping that from you, what else aren't they telling you?!

I'm voting CIA!!!