I don't know how to go about dealing with this - any help?

My girlfriend, as much as I love her dearly, has broken a forty year old acoustic guitar which I was learning to play. I have memories of my mother playing that guitar when I was a child, and it sounded so beautiful, and now it’s broken.

My girlfriend was very drunk, broke a few things by being in a drunken stupor when I was asleep, she’d gone out, got some more booze, came back with it, then proceeded to be….thinking of killing herself and shit. It was rough, so I had to stay awake to make sure she didn’t do anything fucking stupid to herself.

I can’t seem to get her to stop getting drunk and breaking my stuff. It might seem shallow, but last year she broke two of my favourite glasses. One was a Bailey’s glass, and the other was a Jack Daniel’s glass. I didn’t bat an eyelid, and I said “Glass is replaceable, but you are not. So it doesn’t matter.”

This time, though, it’s different. Anyone who knows anything about acoustic guitars will know that they do not sound the same. They certainly do not, I have played a number of them and they all sound very different one from the other, and this one had a lot of sentimental value to me. I was mad, but I wasn’t mindblowingly mad. I didn’t vent steam or rant or rave at her about it, but in my mind I was livid. I’m not mad about it now, but I am pretty upset because it was a part of my history, it was a part of my being able to be creative and do creative things, creativity is my thing and now, one of those means with which to be creative is destroyed.
I can’t afford another guitar.

I love her but I do get pissed off with the breaking of my stuff – whether if it’s by being drunk or not and I just don’t know how to deal with the shit without being confrontational and pretty brash about it. What can I do or say to make my girlfriend understand that my stuff is my stuff, and I’d rather she didn’t get so drunk as to start wrecking stuff by falling all over the friggin place? Worse still, she says it wasn’t her fault, it is like a total denial of anything wrong having happened in the first place.

My GF has borderline personality disorder, which does make things interesting, so the “black and white”, “completely wrong or completely right” mentality she has makes trying to get messages across sometimes pretty difficult.

I’m not ditching her for the sake of a guitar – but clearly, something needs to be done to address the issue without having to part ways. Suggestions from BPD sufferers would be probably pretty helpful on this one (I know you’re out there) and even if you’re not someone with experience in handling things like awkward moments with an SO who has BPD please give it your best shot.

Thanks for your time, and I’m really sorry this has been – wow – so long, but it’s really doing my head in and I need some sort of guidance on this one pretty badly.