At the core, is she Dr Jekyll or Mr Hyde?

[TeaWithMilk]

I grew up hiding from my mum, texting my sister whenever I detected the slightest change in her demeanour, trying to change my behaviour to please my mum with no success.
I grew up thinking her outbursts of intense anger were my fault. Hiding in my room, shaking with every door slam, object throw, insulting scream. And then 10 minutes later, back to calm- no acknowledgement for the screaming, no apologies for the insults, 'no memory' of them happening.
Although I am no longer a child, her violent screaming still reduces me to one. I don't think I ever feel the fear and anxiety I feel when she screams, even as I know I have done nothing wrong. What is she capable of? What if she physically hurts me?
I feel very grateful to have moved away from home at a young age, and to be able to live my adult life away from her. This is a privilege I don't take for granted.

But in the midst of this pandemic, I have decided to return home and now I face her yelling wrath nearly every day, as I try and study for my life-defining end of university exams.
I'm shocked by her lack of empathy with my current situation. As I see the end of my university career take place in an uncertain, heartbreaking way, and as academic pressure weighs down on my shoulders, she can spare me no compassion. If I don't read her mind and do every little thing she expects me to, I am a terrible child.
I don't want to leave home yet and go back to my university town and to my small apartment and she knows that. She hangs it over my head in an attempt to make me bend over backwards to try and stop her rage.

It's really hard to understand which one is my mother. Whether it is her vengeful malicious yelling self or the one who laughs and dances with me. What is her real opinion of me? The one she gently shares in the good moments or the insult she yells when she has reached a breaking point?
It's only been a couple of days since I found the name BPD to call the behaviours that have shaken me since I was a kid, and while I don't want to label it without professional help, listed behaviours and tendencies of people with BPD all ring very true to me. I've started reading books about healing and about setting boundaries with her to prevent hurt more, but I worry that this hope I've been feeling about her issues will dissolve once more. I'm getting tired of trying to fix her and parent her. I'm tired of my sister and I being her only friends. I'm just tired of taking responsibility for her explosions, even if now I'm taking responsibility by setting boundaries for my own good.
I wonder if my relationship with her can ever change. I wonder if I am foolish for being lured back in during her nice moments, just to be slammed with her rage a moment later.
Are her good times worth the pain?

[Methuen]

Hi there Teawithmilk!

Having a BPD parent is so hard.  It's also a disappointment, because we can never have the relationship with a parent that our friends have with theirs.  And it's hard to stop wanting what isn't ours.  We keep hoping right?

I don't want to leave home yet and go back to my university town and to my small apartment and she knows that. She hangs it over my head in an attempt to make me bend over backwards to try and stop her rage.

Staying with your mom must be offering you something that your apartment doesn't?  Are you able to identify what that is?  

How does your mom know that you don't want to go back to your university town?

Many of us here have found it helpful to not share information about ourselves with our BPD parent, because they can use it against us.  It's a difficult thing to realize this, because it's a parent and we're supposed to be able to trust our parents, but BPD kind of messes that up.

It's really hard to understand which one is my mother. Whether it is her vengeful malicious yelling self or the one who laughs and dances with me. What is her real opinion of me? The one she gently shares in the good moments or the insult she yells when she has reached a breaking point?

This sounds like splitting.  If you haven't already read about splitting on this site, check this out:

https://bpdfamily.com/message_board/index.php?topic=62033.0

but I worry that this hope I've been feeling about her issues will dissolve once more.

What are you hoping for Teawithmilk?

I'm getting tired of trying to fix her and parent her. I'm tired of my sister and I being her only friends. I'm just tired of taking responsibility for her explosions, even if now I'm taking responsibility by setting boundaries for my own good. I wonder if my relationship with her can ever change.

I see this as positive for you, since it suggests you are getting closer to perhaps accepting the situation for what it is.  As to whether your relationship with her can ever change, it depends what you mean by that.  In my case, I realized my mom's BPD was never going to go away.  I finally stopped hoping she would change (or I could change her), and so now I still have a relationship with my mom, but it's not a deep or fulfilling one.  I support her physically, and also emotionally, but I support her in ways where I also look after myself by setting boundaries.

I wonder if I am foolish for being lured back in during her nice moments, just to be slammed with her rage a moment later.

No you are not foolish Teawithmilk.  You are normal, because it is a very normal thing to desire a healthy relationship with a parent.  

Best wishes for your last term and exams!  Stay focussed on the prize of finishing.  Don't let your mom's drama get inside your head, and interfere with your exam prep.  Do you have strategies to cope with the stress of living with her?

[lexialpha]

I feel that I have wondered those same thoughts about MY mother.  You have come to the right place! Once I realized that all of that anger was not about me...and this is NOT about you... then I could to began to heal. You will come to realize that there are feelings that she CAN'T feel. Empathy is not at the top of the list of feelings for those with BPD. Emotional distancing was the most helpful for me.  When she has a biting remark, know that it is not something that you said or did, it is just the way that she responds to things not going her way. It's kind of a tantrum, in a way. She never learned to manage her feelings and so has outbursts. You can do this! You can redefine your relationship. It doesn't even require her participation. Love and luck.