In my opinion,we're all broken in some way, we all have borderline disorders, a lot, or a little. It seems like the people who have done enough work to know and own their own - to not fall into old roles and are able to reflect healthy attitudes and perspectives are probably people that worked on that really hard, started off with that in life, or sometimes people that went through being the co dependant 'fixer' and realized they had to protect themselves at some point, and try to unlearn co dependency.
Whatever it is for you, I feel sad for what you went through for this person, and I hope you will find a way to protect yourself from being hurt in the future by taking to heart the good advice you're getting. You have a difficult task, finding healing for yourself and unlearning some deeply rooted habits in relationships. But you can do it.