AITA won't let me post but I need to know you're perspective! I don't want to pay my mom monthly pocket money!

I (29F, Indian) was an accident-kid and my mother (72F) had me very late in life. My mom was a SAHM whose whole life revolved around my sister (40F), while my dad was struggling to keep the family business afloat. Favoritism was blatant and I always ended up being the neglected child. My father always made it a point to spend some time with me in the evening when he got back from work but he'd be so tired, it would mostly be reading the newspaper with him (he never had a Saturday or Sunday off so it was only the evenings). As I got older and I was aware of the favoritism, I became depressed. Apart from knowing how I was treated differently, I was always told how my sister was awesome at everything. 'See how well she sings!' or 'She is so intelligent!' or 'She is so street smart!'. I on the other hand had talents, like I played the piano with no training, was a pretty decent artist (by a 11 YO's standards), but didn't see the same kind of appreciation from her in front of people. I started keeping to myself and my dad thought it was because of me getting into my teen years. I noticed how my mom splurged money on classical music training for my sister (my sister hated this at the time) while I never got to attend drawing classes or piano lessons to build on my talent because we were 'poor'. It didn't help that my mom would jokingly tell me that they weren't expecting me and it made finances more complicated for them. I hated being alive and all I wanted was just to be loved. I tried spending more time at my cousins but now that I'm older and remember how my cousins mom would talk to my mom, I understood that her 'love' was only to taunt my mother about how I loved them more than my own family. I never got to listen to the end of how I should love and be with my own family.

I always tried to find the love outside of home and I guess thats what screwed my mental health. At the age of 14, I was sent to another cousins house for the summer(my sister was getting married and the extra love and attention to her, with none to me was driving me nuts and resulting in arguments) and grew very close to the uncle and aunt, especially the uncle because he acted like an older 'friend'. I was innocent and didn't understand the s**ually inclined behaviors he exhibited. During the wedding, I was looking forward to meeting said uncle and aunt, but unfortunately, he molested me, in my own home, in my own bed. I was just dead inside after that. My mom thought I was upset that my sister moved to another state after the wedding but I didn't trust in her to tell her. After that started my binge eating days, battle with PCOS, and being made fun of for being fat. There was not a single minute of my life where I felt glad to be alive and no one in my life understood me.

Meanwhile, my sister was settling down, got a decent job, had a kid and my mom was fawning all over her and the kid. My sister always took my mom for granted, she was in her late 50s when the grandkid arrived and my sister would leave the kid at our house everyday so she could go work. My mom happily took care of the kid. In all these years she never even noticed that her other daughter had some mental issues going on though. When my mom was 60, she had a hysterectomy which went horribly wrong. She remained in the hospital for almost 3 months before she came home. She was weak and her stitches had still not healed (she developed stress induced diabetes and her sugar wasn't under control, which caused her wounds to take so long to heal). During that time, I took care of her because my sister was married and didn't have the time with a kid and husband. Along with taking care of my mom, I was also taking care of the kid when I wasn't at school (I was 17). After her wounds healed, she wasn't the same person. She was constantly irritable and weak so I did everything I could to help her get better and dealt with the anger and frustration she felt while my sister had a good time earning money and having someone care for her kid. My sister kept moving from state to state and even though my mom was so ill, she kept following her to help her with the baby. We don't have the social system where kids leave home when they're 18, so I continued to live with my parents after that. My sister had a second kid who was also with us every now and again. I was in undergrad and was busier with school so I didn't see the kids as much, mom handled everything. But obviously, she was older and weaker so she couldn't manage anymore, but I was the one to receive the frustration in the form of shouting matches.

After graduating I got a job at a good company but had student loans (which my sister didn't have because we could afford her school fees, but not mine). I had a horrible boss and literally rotted at my company for 3 years even though I knew I had the capability to grow, if provided the opportunity. I couldn't lick a**es which prevented me from growing, which depressed me further. I decided to fund myself and go to the US. My dad helped me clear off the last bit of my loan so I could go to the US debt free (kind off...I had to take a loan to get here). I worked really hard on my applications and the day I mailed them out, my dad died of a heart attack. I was broken because I really loved my dad. He was always there for me even though he wasn't very loud about it. All this while when I was working, I wanted to give my parents a better life. I'd take them out to fancy places, buy them better clothes, improvise the house, pay bills, basically do things we wouldn't do because of having no financial means. My sister progressed professionally, but never contributed to our home financially. She would buy clothes as gifts once in a while but my mom always asked her not to, because she had a family. After my dads death, we came to know that my dad had tremendous debt and I handled all the issues and supported my mom by taking almost 2 months of leave from work. Everyone expected me to crush my future to live with my mom in India. I didn't want that for myself (I was 26) and I left, even though I heard a lot from my sister, who literally got married and left home at the age of 22, not having dealt with the worst side of my mom or taking care of her in her old age/sickness. I got a job here a year ago and the field that I'm in doesn't pay well. Thankfully I live with my family (fiancé and a pibble) and together we manage well. I pay about a $1000 as monthly installments for my loan, apart from other expenses I have. I barely get $3000 a month in hand. My mom called me the other day asking for a monthly pocket money amount because she has no earning means and my sister has a family and has spent enough when I was studying here. I don't feel like paying her a penny. To add to the favoritism, she payed for my sisters wedding and bought her gold, but now for our wedding keeps crying about how she doesn't have money but worries about what people will say if she doesn't pay (not that I asked her to, my fiancé and I are saving for it). AITA for not wanting to pay her?