Hi Virtual. It must really hurt find that your mother has lied to you so many times. Sounds like she does not like herself or the things she does , that is the only reason I see for her to lie to you.
I think you are right to stay with your dad. If you feel comfortable with your dad stay there. Find out what you want to do with your life and move forward. Now that you know the truth try to put it behind you. Go back to school and do what feels good for you!!