Hi mssalty, That sounds tough! When communication breaks down we tend to get caught up in all the little details. I know how much it hurts me when I do not feel understood. As hard as relationships are in the first place, my partner and I come from different cultures and have different native languages so there is always something lost in translation I am afraid.
I find the more I can slow down and de-personalize, and put myself into a mind frame of patience it helps. We can't change or control others so oftentimes the fastest solution to improving thing is simply to work on ourself. This can be hard too if we do this with the mindset that we are trying and no one else is, this can lead us to feel even more hurt.
I find when I understand that others are doing the best they can with the tools they have I can at least de-personalize a bit. I dunno, these are just small mental adjustments I try to make to bring myself a bit more peace with all of this. One funny thing is that since my partner is male/an engineer and likes and understands the concept of "tools" and using them, when I present new ideas to him in the form of "tools" we can use he is very receptive. Okay, he may not be able to use them all right away, or fall back into old patterns, but I have to believe that some of this new information I bring to him means something, if nothing else giving him a bit of security I am not leaving him and I am trying to make improvements that benefit us both. I always try to create a "team" mentality in our relationship, and he has really taken it up. He always walks around, when in a happy mood with me, saying what a "great team we are." (But my guy does not have all the BPD traits and is very high functioning I should add.)
Today I feel a lot of anxiety and am recovering from the 5 day "break" I just went through. I feel overwhelmed, and unable to function at 100%. I trust that this will improve, but the fear of the "next one" is always inside me. But really, I must put that away and focus on now. There is joy in today and in now. I want to be proud of myself that I survived another storm and did my best.
Perhaps one idea is to find ways to connect. I know. I can't say I feel totally connected to my partner. He wants me to tell him everything I feel, but I simply don't want to because he has a habit of using anything against me in later disagreements. He stores away anything he can use to hurt me with at a later date. It is terrifying really. But I do make an effort to have some connection. We had a lovely time of connecting/talking last night. It is not as much as it could be, but I was proud of us for having at least that.
I am a bit like you it sounds like. I get tired of explaining and repeating myself. It feels constant and like a burden. On the other hand, no one can read our emotions and minds, especially those with serious issues related to emotions as this, so if I can do at least a little of this and then find ways to renew my human well of patience that helps. Maybe that could help you too? For example, yesterday I apologized to him for not always having enough patience with him. It felt good to say so and he felt good that I recognized this and wanted to help. He knows I am working on it and why - for both of us.
Maybe if you thought of at least some of his questions as attempts to connect, rather than as annoying attacks it would help. I know, the wording people use with things can sometimes drive you nuts!

Also it helps for him to hear apologies (for anything) so he does not always feel like the "wrong one" who is always messing things up. If I made him into that (the wrong one/the worse one) it would just add to him feeling worse and hopeless so I do not do it, though boy does he bring problems and chaos!
And so it goes... .the ups and downs and intricacies of all this are a lot! Wishing you some peace and happiness today!