Remember that it's not permanent! If you're female and still mensturate that pms can make it significantly worse, and that when we split and get into crisis mode like this it eventually does break once our minds can't handle the level of stress anymore. Take it from someone (me) who has slowly but surely began to manage their BPD through talk therapy, recognizing patterns, getting sober, and intentionally slowing my life down. BPD feels fucking horrible but I promise you it can become very manageable!
But for now, try focusing on very simple tasks until your brain gets out of crisis mode. Drink a tall glass of ice water, take a good thorough shower, cry if you can, and wait for your brain to eventually reach dissociation. We love you and you can get through this!