AITAH for getting mad at my dad for still being in contact with one of his former students?

My dad is a teacher at the same school I attend and last year, while I was in the hardest grade level of high school, he spent a lot of time trying to help out this girl that was, and is, a grade above me. She’s graduated now, but at the time she wasn’t. She would go in his class everyday, do practically anything he asked for, and overall was at least tolerable before everything unfolded. Apparently, she was struggling at home because of the negligence she was receiving from her mom due to her having a new boyfriend. Her dad doesn’t live in the states, and her mom doesn’t live with her anymore because she, at the time, was over the age of 18. After hearing about this, my dad decided to start helping her out. This really wasn’t a problem at the time, since I viewed it as an act of kindness, but things started getting.. weird. And by weird, I mean he started picking her up after her job shifts, buying her food, constantly having her over, and even getting invited to random family events. Even to my own birthday party, without my consent to it whatsoever. I struggled a lot that year, because not only did my mental health have the worst decline, but I was failing a lot of my classes and in a super unhealthy relationship (which I’ll talk about probably next week). When I needed the most help, the most attention, my dad, and even my mom, practically just threw me to the side and told me to deal with it because they valued her needs way more than mine. This complete and total stranger, that had her own job, her own form of help that she was already receiving by her friends, and in a much more mature mindset than I had at the time to understand that what was going on was getting out of hand, became a sort of parasite to my parents. Maybe I would’ve been a little more okay with it if they were helping out someone else, but it was only her. After multiple talks with them about this situation, and after family members pointing out how weird it is since my dad started going out of his way to joke around about how he’s his “new daughter”, they slowly stopped over the summer. However, she started texting him again at random and even though those random visits stopped, she’s still trying to find a way back into my dad’s life after she already graduated. Now she’s asking for help with college, even if she confirmed she’s completely fine and most likely doesn’t need the help. She’s turning 21 this weekend, and my dad got mad at me for not wanting to go to her birthday party. In turn, I got super mad at him for even asking. I really do feel like these feelings just stem from jealousy since I never in my 17 years of life got attention from them the way they do for her, but it makes me uncomfortable that someone who claimed just needed help is still trying to be a part of my family like that. I feel dumb after typing this out.. but I really need advice on this.