New to this, help!!!

Looking for anyone with past experience/insight with family members with BPD.

My (20f) sister (23f) is diagnosed with BPD. She just left college (still has some credits to complete) and moved home, which is where I am for the summer.

Over the past year, I’ve noticed her self-destructive habits get really bad. We used to have a really good relationship and were really close, but as she fell into addiction and continued to embrace unhealthy relationships, our connection seems to have disappeared. She has lost all her close friends in multiple different pretty big blowup friend breakups and doesn’t really have much going well for her right now. I definitely still feel like I’m grieving the relationship we used to have :(

Now, living together again, I’m really struggling with basic things like simple conversations/“confrontation”. I don’t know how to discuss issues with her without it being “triggering” and sending her into a space where she belittles me or gaslights me. She is a chronic compulsive liar, which is the thing I struggle most with. I don’t trust anything she says anymore, and if I catch her in a lie, game over. It’s like a switch is flipped.

I’ve started recording some of our interactions because she would lie to our parents about things I said and would gaslight me in future encounters, claiming she never said things that she did. When I brought up her lying and said I had proof, she freaked out and told me and my parents that she didn’t feel safe in the house because of me.

I’m certainly not perfect and have things to improve upon in my own communication. I’m trying to balance listening and hearing genuine feedback that I should work on in these instances with protecting myself and creating boundaries if she starts to lie/gaslight/etc. but I’m having a really, really hard time toeing the line between the two. Does anyone have recommendations on this?

I do go back to school soon, but would love any tips and insight for when we are inevitably together in the future and for the next few weeks.

Thank you!!