How do you stop a cat from peeing in the house?

My cat is a few years old, never had a problem until now. She keeps peeing and pooping on our carpet. It got to the point where my dad got really mad at her and ed her. It scared her to death but it didn't stop her. When she does it and you find it she hides, she knows it's bad. We've tried sprays to deter her but they only worked for like a day. We've tried tin foil and she would just find a new spot to go. We would move the litter box but don't want to screw it up for my other cat. We tried adding a second litter box but the cat won't use it. Today we are going to get a bigger litter box to see if that helps, (it worked for my Aunts cat.) My parents are on the last straw and they said if we don't fix the problem we are getting rid of her. Please help, I love my cat and don't to get rid of her!