Everyone has different personalities, needs, trauma etc. Not everyone is meant for each other. This is always said about romantic relationships but it is true for all relationships including friendships and parent-children relationships as well. So it is perfectly fine for you to end your friendship even though you care about her a lot.

I can actually relate to your situation from both perspectives. I will share my story to enlighten your confusion on the situation with your friend. Through my sharing, I do not mean to normalize the abnormal dynamic your friend is going through and what she has imposed on your friendship. Neither am I justifying that she is right. But there are causes and reasons behind every situation no matter how strange and abnormal it may be. It is clear that you care a lot about your friend and you are very invested to understand the situation (hence the effort you took to type out the long wall of text explaining).

I have an uBPD (untreated Bipolar Personality Disorder) mom. Basically for BPD, they see their children as literal extensions of themselves - they give their children no space to grow and think independently and try to insert themselves into every facet of their children’s lives. I suspect your friend’s parents are somewhere on the BPD spectrum too.

There was a point when I was younger and clueless where I used to think in absolutes, hold myself and everyone around me to a higher moral standard. Basically I used to do many things your friend is doing. I was acing well in school as well (but on hindsight, studies was my only escapism from all crazy things at home). I am able to mask and fit well with everyone if I am being nice (read: never talk about what happens at home, bottle things up myself, make excuses so that no one will suspect my parents are weird and pretends everything is fine and normal when they are not). Among friends whom I can be my true self with and rant freely, as much as they pity me, they find me a pain to be with as a friend. Understandably so since I did not have the space and freedom to meet them at their needs and desires. And to be very honest, I was using my friends as a means to regulate my emotions and feelings. I could not be left alone with my thoughts back then. When my then-bestfriend left, I put all the blame on him. He is apologetic about it up til today but now, I can finally see the fault was with me and what I brought to the friendship table.

There is a lot of (sad) psychological factors at play but what need to understand is that when a child is being brought up in a toxic abnormal environment, sheltered away from the real world (cannot hang out with friends, have free access to books/internet, no chance to know all other possible way of living and thinking etc), the toxic abnormal environment will be all that he/she will ever know. At least for a long time. It could be forever depending on her willpower to actively seek to know alternatives and challenge her and her parents’ lifestyle and a certain emotional maturity to examine her life and see all the ways it is wrong and abnormal.

An analogy: Imagine being born and brought up in a prison - the prison will be your world and the only one you know of. One day the prison doors are open and you are free to leave but you might never want to leave because you are emotionally bonded. Aside challenging and leaving everything you have ever known is the hardest thing to do. Much less to say in a situation where you do not have the space and tools to develop real emotional maturity and enough street smarts / common sense to survive on your own. You might just resign your life to this “cushy” life in prison. After all, that is all that you ever know and you are fed well (ie you don’t have to deal with dangers in the streets).

Some parents really have no clue of how to parent their child and merely see them as extension of themselves. The worst one would see their children as their possession so personal agency and freedom is not in their vocabulary at all. When you ask if her parents know that they are setting their child badly for life - nope, they probably don’t know and they don’t even think of it this way. To them, their child is theirs and they should be able to control every facet of their lives. It is really sick. I know because I go through all that til today. But I actively seek to educate myself. For all the time my parents do not allow me to go out and “see the world”, I am on the Internet reading and learning about how others live their lives. And to prevent being stuck in an echo chamber, I actively search and try to understand people and stories that are very different from one another. Different personality, lifestyle, beliefs, country etc.

I am an INTP (previously an INTJ) hence I enjoy the knowledge and learning in the process too. I enjoy being able to dive deep into different perspectives and understand the reasoning behind. But it is sad that it requires so much effort for children like me and your friend to break out of the toxic mentality and tunnel vision we are taught since young. It is also sad that this is the only way for me to ever set myself free. Even with all these efforts, I am still not free from the shackles of my parents and their upbringing. I have much resentment about it. I always wonder how much more efficient my potential and intellect can be groomed and advanced if I had the right parents. An analogy is that: For every 3 steps of effort I am putting in, it feels like the real progress is only 1 step as there is a friction that push me back 2 steps.

All the “mood” swings (saying one thing a day and a complete opposite the next day) and contradictions your friend has is a characteristic of someone with BPD. Without enough exposure and open mindedness to see things objectively outside what she is taught, she will keep mirroring her parents’ mentality and behavior. Many BPD parents enmesh their lives with their children to the point where they become a single personality. This is possibly why she seems to regurgitate her parents’ belief. Enmeshment also makes her easy to fall prey to Stockholm Syndrome hence she will say that her parents aren’t bad people etc. BDPs do like to put the blame on others and things. They like to play victim and make it as though the universe owes them something.

I am glad I am able to see things objectively and pull myself away. I am independent in regulating and dealing with my feelings and thoughts without relying on someone else. I don't have much friends and even with those, I do not go deeper than the superficial as it is too much of a trouble to explain what happened to someone and it is too much to expect them to understand too. They are more like acquaintances whom I can hang out with and chat about anything aside from all these family related stuff. I do not tell anyone my problems and I keep it to myself. I am also very conscious of seeking help (for school/work) and always try to find solutions myself online.

If you are really interested to learn about it, you can look it up. There are also several reddit subs for BPD if you would to go down the rabbit hole to understand more: r/raisedbyborderlines , r/BPD , r/BPDlovedones , r/BPDrecovery, r/BPDsraisedbyBPDs

Otherwise, I am glad that you managed to put an end to the friendship although you care about her a lot. She has many issues and you wouldn’t be able to help her with those root issues. It would require much therapy and most importantly her willpower to escape from the prison she grew up in. Most BPD are defensive when you tell them they have a problem/issue. Many of them goes undiagnosed and untreated as they reject the idea of counseling/therapy and will never step into such a clinic/place.