AITHA for being jealous of my five-year-old sister?

(I had to reply to my post because I had some problems editing.)

I (20F) am jealous and even have some selfish thoughts about my five year old sister with our mother.

It sounds dark or very weird, I know that but I needed to vent about it without that feeling that I'm doing something wrong or that my problems aren't as important as the of other people. In short, my biological mother did not raise me and was manipulated and suffered several abuses during the time she lived with her aunt. It's a very long story in which my mother and I were victims of the same person who I would call Maria.

Maria was my mother who "took care" of me until I couldn't take it anymore and moved to another state to live with my biological mother. She is a narcissistic woman and her husband and children knew about her evil deeds but none of them told me the truth about my real mother, they just stayed in silence or they patted Maria on the head saying that I should understand. She told a lot of lies about my mother saying that she had 5 abortions before me, tried to abort me, abandoned me or something like that but I never believed her and I think that's because I was a child who just wanted to play and didn't care about those things so I never got angry with my mother or believed Maria's lies.

I don't want this to be too long so I won't go into too much detail but thanks to Maria I have had a lot of mental health issues, severe depressive periods, self-esteem issues, social anxiety, image distortion, anger issues and the main thing is the fact that I am always repressing my feelings because it was imposed in my head that there were people (adults) with real problems and I should say thank you or something. I never thought that the things I went through with Maria were affecting me so much until I moved and lived with my mother and realized that I was in an abusive family cycle and that many things that they did to me were very wrong.

It's a long story, I could write a book about the few things I remember which are still many but I'm summarizing as much as I can. I knew I had issues with my mother but I didn't think it would be so serious, Maria said she loved me but when I confided something confidential she used it as ammunition to tell others people so since I was a child I completely lost trust in her and never told her anything else about my personal life because I knew she would use it against me. So it was very strange to live with my biological mother and see how she treats me with respect, listens to me and gives me advice and gives me this feeling of comfort that I can trust her with absolutely everything. When I saw commercials about Mother's Day saying that mothers were a child's best friend I used to scoff but now I have the privilege of having my mother as my best friend.

Maria's daughter took care of me when I moved to the city (before I lived on a farm) to study at a private school, but living with her was a nightmare too. I think my aunt was verbally abusive because she would come home from work at night tired and take it out on me or her sister-in-law who was also a child all your anger and especially if the house was even the slightest bit messy. Many things happened then while I learned to repress my feelings due to the idea that there was always someone truly suffering and what I had was nothing. I was always a distant child trapped in my own world creating false scenarios in my own world because I was lonely and had no one but myself to play with. I don't think my lack of friends or the two years of bullying at private school affected me because again I was always alone so I enjoyed my own company more than that of others people. Maria also didn't allow me to go out, she didn't let me go to some birthdays or stay at a friend's house to do some school activity, and even when I had my own vehicle and wanted to go out with my friends at night she would always call me to come home so I stopped leaving the house because I was tired of her complaints about my safety.

So, I'm a 20 year old woman who doesn't have any friends other than my mom and cousin, I don't leave the house unless it's with my mom or my cousin and I think I've developed social anxiety because I've always I start to feel sick just at the thought of stepping outside the house or being around other people. I'm not someone who is visibly depressed or anything like that, I'm a very happy person, the beautiful clown of the family, but less sociable so when I tell someone about my life problems people don't usually believe it.

So, last week was my 5 year old sister's birthday and she got a pair of roller skates and I think that was a trigger for a problem I didn't even know I had. I grew up with the basics and that sucked so seeing my sister had something I always wanted as a kid made me jealous (weird, I know) and I wished my mom would do the same for me even though the one who gave the gift was my grandmother. I know that I am an adult and that I shouldn't compare myself to a child and that I can work to buy roller skates or sneakers but it's not the same thing. Sometimes I wonder if I would have been different if my mother had taken care of me, if I would still be this adult with the soul of a child. I want to believe that I'm trying to make the most of what I couldn't as a child, but I'm still seen as a more childish person (not in a negative way) by my family and Children usually like me because I'm kind of in the middle of them because I want to play too.

I was neglected as a child so I was admitted to the hospital due to my poor diet, there was a time when my mother came to try to take me with her without success (again) and had to take me to the hospital. I also had problems with hygiene, I don't remember being taught how to brush my teeth as a child and had to learn from other teenage girls at school about wearing a bra and deodorant. Maria didn't take good care of me and was always demanding things that she never even taught me and wanted me to learn by force and in a few minutes. I want to make it clear that I don't hate my sister even though it's very stressful to take care of her but sometimes I feel jealous towards her.

I don't know what I'm looking for here on Reddit, I know I should go to therapy but I don't have the money for it. I know I should talk to my mom about this but I can't, I feel like my mom is kind of ignorant about this but I'm not sure so I don't want to embarrass myself by telling her that I want to start therapy. I plan on getting a job to do this myself but that still seems like a distant future so I'm typing this out to strangers to get some input other than telling my mom.

I tried to tell my cousin but she's a lost cause too saying I don't need it, I am surrounded by people who have gone through many difficulties in their lives and sometimes I think that I am being too dramatic and that nothing that happened to me in the past was that bad. I look at other people my age and even people younger than me with their lives almost made while I haven't achieved anything yet and I'm jealous of a child just because I didn't have a childhood. My mother says that none of this is my fault since Maria didn't raise me to be a functional human being, just a puppet for her dark tricks, but that doesn't take away that feeling that I am being useless or a great burden. I think I need a job to have real concerns on my mind and I'm looking for that, Older people often say that depression doesn't exist for those who work and that it's just a fad or something from the devil for those who are more religious.

This is very long but I have no other place to express what I feel and seek some result. Am I an idiot for being jealous of my sister? Is everything I feel nothing compared to other people? Am I weird for still liking more childish things? Was everything I went through normal and something I should overcome or do I need help? I want to say that everything is fine, but sometimes I realize that I am getting more mentally damaged every day even though I am no longer exposed to any kind of abuse.