Have you dated someone with Borderline Personality Disorder?

A few years ago I was in an 8 month relationship with a 22 year old man. It started really great. He showered me with affection, wanted to see me all the time, and would stop at nothing to make me happy. I was delighted because my previous partner was not very attentive. It felt like I was finally in the relationship I wanted. Shortly after we started dating, it became clear he was experiencing some anxiety. He would become very emotional, cry often, in situations where it didn't seem appropriate. He said he loved me almost immediately. It was a very intense time and I chalked it up to someone who didn't have much relationship experience learning the ropes. Eventually things got very volatile. It culminated in him swerving my car into traffic, nearly resulting in a major accident. He finally sought psychiatric help. The relationship ended shortly after. 
He was diagnosed with Borderline Personality Disorder later on. 
I find myself thinking of him often and wondering why I didn't see the signs sooner. I feel ashamed because I don't think he ever values me. I feel I was simply a vehicle for his mental illness, or someone to obsess about.
Has anyone else experienced this or dated someone with a serious mental health issue? I would love to hear about your experiences. I would really like to put this behind me but I'm having a hard time doing that. 
Thanks for reading!