There are few things I still do not understand about BPD.

My (ex)girl (diagnosed BPD) is treating everyone who care for her and who she cares about like crap since June. She had traits of BPD before, but this is her first severe episode probably triggered by mega stress. Her decisions are risky, impulsive. She lacks empathy towards ones who she cares about the most, especially me, but somehow functions in the outer world. It's only about her for quite some time and is constantly seeking attention from others and something more, that really doesn't even exist. When wanting to help and being concerned by her parents, she feels like they want to control her. Is raging, irritable and such. We do not have any contact for a month (called me 7 times though in 3 days) since she probably cheated on me and is with that guy, who she doesn't even like. When this episode started she told me she f***ed up from the start for letting me so close. But when she was well she was so glad that she opened up to me, so I showed her what it means to be unconditionally loved and supported for the first time. Then there were days of confusion, that she felt love for me, that I'm too good and doesn't deserve me, that she can do this... But since the end of September this all vanished. Complete emotional blackout. Her life has hit rock bottom. She is thinking with her feelings.

So my questions are: 

How long do these "episodes" last? I know it comes to the individual but can it really last for months? And can she realize what she had done at some point? She is being hospitalized soon and she approved it. Can this help her in any way? Why do you get hospitalized? Are these times characterized with being unwell and there come times when you function normally, or is it like this all the time? Is there a crash from this or is it just slowly getting better? What can cause someone to crash into reality back? Is she distancing from loved ones cause we/they are triggering her?

Hope I'm not asking too much but it would certainly help a lot. I know it's not her to blame.