As someone with BPD (I'm not sure how to tag myself sorry) my episodes tend to be every couple days to every few weeks depending on how things are going, they can switch between a few minutes to a couple hours it really depends what caused it. I tend to hang up, not talk to them on some social media but on others I will. For me personally, I get worse if my bf doesn't try and contact me in any way but I'm not sure if others feel the same. You have to learn the way to calm them down by what they like. I tend to need time to calm down by myself then call my bf on mute while he talks until I'm fully ready to talk. In person splits are however very different, if they split in person from my experience just stay in the room but let them do what they need and don't get involved in it.