Is this jealousy?

I am twenty one years old and about to finish school. I am in a vocational school about to earn a certificate in medical billing. To get to the point, my younger sister is heading to college in two months. She's going to the college I have been wanting to go to since I was thirteen. When it was my time to apply to that school three years ago, my parents didn't let me even apply. I took the SATs and got good scores, earned satisfactory grades, and had good behavior all four years in high school. But when my parents talk about my sister and school, I get so angry. And when my mom talks to me about it, she always tells me that we didn't have money at the time. But at the time, she and my dad were earning great money, a lot more money then today. And I was going to take out a loan and apply for grants. Since then my parents have taken major paycuts to work closer to home. I just do not understand why? Any advice?