How to explain my BPD to my wife?

She knows I have a mental illness but she had only assumed it was bipolar/depression. I thought the doctors/my parents had told her after my numerous psych ward stays since we've been together.

I got kind of mad at her earlier because she didn't know and told her to just look it up. I know that's the wrong way to go about it.

How the hell am I supposed to explain how I'm feeling when I don't even know? The last week or two have been especially hard with very intense and rapid mood swings. A little bit of SH but I stopped that just so my kids wouldn't see the evidence.

I don't know my brain hurts.