blackandblue...
I have a recently informed theory as part of my tool kit and offer it up for you and others to consider.
I have friends who work in CD counseling, and one of the treatment centers which is run by the Stephanie Covington model is this: that personality disorders (such as borderline and such) are actually reactions to trauma. They actually do not even use diagnoses such as BPD and instead deal directly with the trauma that is causing the disturbance...trauma both personally historic and current.
What I realized at one point... as I rode the wild ride of painful, cognitively dissonant, confusing, crazy-making, trying-to-make it-work and traumatizing process of trying to maintain relationship with the addict I loved...was this, that the psychic/emotional/spiritual jerking around that I was subjecting myself to (by loving someone with a deep splittedness) was causing me to go down my own spiral of deep and sickening confusion.
Add to this the typical personality traits of someone involved in addiction (addict or codependent) such as self centeredness, self pitying and fear, fear, fear...and you have a bad mix of an unhappy life, with sporadic moments of liquidy, elixir like happiness fed by the charming, charismatic (often stylistically attractive) survival skills (how else could they survive!) of a person riddled with addiction.
We become sick.
And here is the catch...as we become more doubtful about our own mental health we can become more apt to blame ourselves in the situation. Our own ptsd is fuel for the blame that gets projected on us by an addictive mind. And we enter into the perfect dance, we fit like puzzle pieces and create the perfect storm, the perfect dysfunctional system.
The long and short of it? If you start to feel any dissonant trauma while you re-engage in this relationship...do not take on deflected blame. Do not engage in arguments and debates. And check the actual possibility of any sort of real reality that can be made out of promises and charm that you hear.
Your inner self knows when the blame or promises are not real, and yet our codependent self wants the promise, wants to believe, and will take on the blame. The gap between the inner self (and its relationship/connection with a higher power) and your codependent self...it is in that space/that dissonance echo chamber/void that your heart gets batted around and traumatized.
Be careful, you are in deep space.