Parents favor sister over brother and I

My dad took out retirement to pay for my sisters expensive university tuition. My brother and I didn’t get the opportunity to go to an expensive college. We went to a local college, he dropped out because he couldn’t pay tuition and had personal issues and I dropped out and finished in my thirties. When I confronted them and asked why they didn’t help us but helped her, they said they “didn’t have the money” for it. They still don’t.

They bought my sisters car for her. They didn’t even teach my brother and I to drive. They didn’t have the money for courses or the time to teach us. They definitely didn’t buy us a car. We got our licenses on our own. We bought our vehicles when we had saved enough money. It took me a decade to.

When my brother moved out, it was “take all of your stuff with you or else.” When I moved out, it was “take all of your stuff with you or it goes to the dump”. My sister (who is in her mid-thirties) still has an ENTIRE bedroom full of her stuff even though she hasn’t lived there for nearly a decade. When I asked why, they said it’s because she’s “saving up to buy a house”. I’ve been attempting to save up to buy a house for 15 years but keep getting set back due to medical debt.

I want to sidebar that my sister is a completely awful human too. She’s rude and condescending to others and sees herself as smarter than everyone around her. She’ll smile to your face and turn around and say awful things about you. I won’t even get into the awful things she’s done to me personally as that’s a whole other story. My therapist believes she’s a narcissist like my mother.

I can’t speak for my brother but I can say that I feel like they are constantly trying to erase me from their lives yet they don’t leave me alone and crave constant control of my life in some way. It’s exhausting. I’m neurodivergent. I have ADHD and am on the spectrum but I was always “the kid they didn’t have to worry about” because I “took care of myself”. It’s because I had to. Me and my brother took care of each-other. I did well in school, made excellent grades, graduated with accolades and went on to graduate from college in two different honor societies and with a 3.9 GPA.

My mom verbally and mentally abused me, my dad was never around for me because he worked a lot.

I’m just trying to understand why they treat me and my brother so differently and find someone who empathizes with me. Help me try to understand please.