Why do i care so much about a friend that doesn't

I want to give a little backstory

I was my friends first best friend when she moved into the country. Our parents are how we met. We would hangout so much when we were younger even though we went to different schools. As we got older we stopped hanging out as much bc yk different schools, high school made new friends, we couldn't drive yet ykwim, but we would still talk a lot whenever we got to see each other it was every few months. During covid when everyone online 24/7 i decided to tell her about my friend (lets call her JJ) that went to her school so they could be friends so they talked a lot online and at school. soon there was gc's with people at their school and ppl online and i started to feel left out but it was whatever. i think they started to notice so they added me to a gc with both of them. I had a feeling that they would talk about me outside of the gc and so i decided to make a post on my spam that said "i feel like 2 of my friends talk about me even tho im the reason they're even friends" they later asked me if the post was about them and i felt like that just confirmed it for me. i told them no its about someone else i met online. Even when we would hangout as a trio i would feel left out. ik im a quiet person but i couldn't control it. anyways some time passes and they have a downfall. JJ spreads some rumors about my friend at their school and talks to me badly about her. I obviously chose to tell my friend whats going on. i was still friends with both of them at this point, some days later she asks me if i'm friends with JJ and i said yes why, she said "i don't want anything about me to go to her" and so i say why what happened she replied "we just stopped being friends lmfao" like didn't care to explain what happened even tho i told her about it was crazy to me. anyways more months later i go over she obviously has a different best friend now and they're like super close, the kind that i always craved to have with her, i understand it might be bc of the fact that she's 2 years older than me and stuff like that but i still want to hangout and talk and have fun.

Now last year my family had left and i was home alone. my mom asked her dad if he can take me to school and he agreed since he's an uber driver. He asked if i can just stay with them instead of being alone at home for 3 or 4 weeks and their house is more closer to the uni so i can just stay with them until my family comes back and so i agreed. I share a room with her and everything is great we start catching up and stuff. a week later when were talking she asks me about JJ if i'm still friends with her and i told her no cause she's been starting drama with people i know and my sister too. She looked so relieved and she goes "omg i thought u were still friends ugh i hate her" i was like noooo. she goes on to ask if she's said anything about her to me and i told her no the only thing she's said about you iv'e already told u about when it happened. she goes on to say i'm sorry btw i should have told u too when it happened but i'm rlly sorry. she says "JJ once told me how she doesn't like how quiet i you are its weird" it just made me sad even tho i wasn't showing it i'm more disappointed on the fact that she didn't tell me when she said that. I said its okay whatever. I remember her saying her and her new best friend of 8 years stopped being friends out of nowhere. I told her that reminds me of someone.

Anyways now I'm still having trouble trying to let go and caring so much for her bc she obviously doesn't do the same to me. i feel like i always do so much for her and all i want is to be cared for the same way by her. i stalk her too much like her reposts even when i try my best not to its sometimes the first thing i do when i open the app. shes married now and we hung out not too long ago but i don't know why i feel attached even tho i don't want to be. i just wanted to be my best friend forever but kept getting replaced. we used to talk to each other about everything. I looked up to her so much and people even say we look alike. I felt like she was my sister that i genuinely loved. I still care about her and i think of her way too much then i should. But why do i keep putting in so much effort thinking she might change one day and let me be her best friend again. Am i emotionally attached?