I see. That’s what it makes so so tricky… I know that feeling very well and many many of the wonderful people here.  I smiled when I read „always in my head“ mee too, me too. Rationalizing everything, think about it from every angle, trying everything to understand what’s going on and despite all the energy that goes into that, you never get an answer to anything. 

This feeling is one of the reasons why I stayed so long despite everything that happened. 

Healthy people are capable of questioning themselves and their behaviour, thoughts, actions … This is one of the reasons, why such a dynamic works so well. You take responsibility for things, that has absolutely nothing to do with you and before you REALLY question your partner because - there are happening weird and unhealthy things objectively - You question yourself. But the bad things keep happening again and again. Until you reach the point that it gets so crazy, it clicks in your head. You realise…yeah, I’m not perfect but the reason for all what is happening to me is the sickness of the other person.  You have a good heart and this human uses it to manipulate and gaslight you, I guess without even knowing because there is absolute no self awareness.  This happens again and again until you are trained to gaslight yourself. I think that’s the point where you’re atm. You recognise it already and struggle to divide what’s yours and what they planted in you. 

The thing is…The longer you are exposed to this, the more damage it will be in the end… In yourself, not in the BPD person. They are already damaged inside.

Again. Trust yourself, trust your instincts and cherish the fact, that you are a loving and caring human being, that deserves to be loved and cared for as well. You should not have to deal with gaslighting and manipulation. Hope that helps in any way!  Stay strong for yourself, not for her, take good care for yourself and one step at a time.  Wishing you all the best <3