It sounds like you've given yourself some good advice here.
In retrospect, did you notice any signs of something being "off" or different about your BPD-ex before you bonded? For me there were, but I didn't recognize them for what they were until, like you, I was all in. Now, I would, I think.
No I really don't think I noticed because she seemed like one of my relatives from when i grew up. The only thing that i was aware of was that she was a little pushy but that was an ethnic trait that I was willing to bargain for as long as she wasn't using it in a negative way with me. For instance, she might say, (my name, come over, it'll be fun.) There were so many things that i still think verbally that made her feel like family that even now it's hard to let her go because of. Once i did recognize the things that were off and brought them up the relationship started to go south (which btw was when she got off AD's).
So in all honesty I did stick up for myself and did address the patterns when they presented themselves which could be why the relationship ended so quickly. However, I still had a hard time pulling away because i justified it was my fault for triggering this side of her and because I so wanted her to be "the one" and overcome the patterns that i saw.
I don't regret having sex with her at the stage of the relationship that i did. I believe that sex is a trigger and without having it one would not really see the borderline or npd traits anyway. It just makes it harder because I bond in that way to an extreme and i'm not good with casual sex. She was resistant to having intercourse because she had gotten pregnant with her ex even after his vasectomy so she was carrying the memory of that. Because of that it made me feel like she was not "easy" and was taking her time before being ready for that next step. Now i'm not sure if that was part of some control game or mind game etc? who knows?