Hi Matilda,
I am sorry that you are going through such a difficult time. Arguing with a pwBPD can be almost like banging your head against a brick wall. Basically, you have to stop making things worse before they get better. There are many tools on this site that can help you during stressful conversations. Have you had a chance to read up on the communication tools? Here is an article to help you get started.
Arguing - don't engageI understand how frustrating it is to walk on eggshells and to be tired of your pwBPD's lack of responsibility. I apologized for my pwBPD's behavior all the time. It was a cycle of him doing something that upset me but, I would apologize for his behavior. Eventually, I became tired and frustrated. I decided that I needed to worry about myself first. It was almost a foreign concept when I started focusing on my own needs more. Having a support network of friends, family, and my therapist really helped me when I was at a breaking point. Do you have a support network?