One of my closet friends told me something during a period of time that I was disassociated. She's now angry with me because she brought it up later and I had no idea what she was talking about. She thinks that I just blew her off and ignored her when in reality, I don't remember anything that happened over the course of a few days. We are close enough that she knows about my PTSD and other mental health problems. I told her that I was disassociated and don't remember. She's now even more mad saying that isn't an excuse to blowing her off.

... what? How to I explain this to her?