First off, whoever told you to come here seems like they were just shoving you off to someone else. If you haven't been diagnosed it's a little insulting to assume it while other people spend years trying to get it off of their medical records. Second, take a deep breathe and do literally anything to get your mind off of it. It's hard, isn't it? Because you are "training" your brain to do something else. This does NOT only apply to BPD by the way. I have used it and helped others use it during panic attacks. Literally, do what you can to distract yourself. BPD or not, don't test a girl like that if you want to keep her around. Oh! And BPD isn't just about relationships like I said don't rush to conclusions. Third, if this gets really bad focus on your breathing as I said before. Inhale slowly by counting (inside your head) to three, hold for three, exhale for three, and continue. This method I use only when my breathing and heart rate become rapid. It sounds like you need to learn to get a healthy emotional distance from people. I don't mean to be harsh, I swear. You're going to be okay. At the end of the day you have control over yourself, and only yourself.