I'm sorry you're feeling that way, the doubt thing. From my own life I can say that doubt is a killer for me. It keeps me kinda frozen in space, in time. I want to make the right decisions and feel as if any decision I do make will greatly impact my children. It will, there's no questioning that. Well, how I proceed with the decisions I do make is what will really impact them, not the decisions themselves.
I questions many things in this life, the status quos, the reasoning for this or that, why one does what they do... .heck even bigger things. My mind just keeps picking away until I can find a sound place to sit on and see what's around me. I'm also a reflective person, too... .but there's much more to me that these two things.
To be honest, this experience with a probably BPD husband... .well, he has me questioning so much, things I can see plainly with my own two eyes, things my family/friends can see plainly... .and I question... .because he says it isn't so or what have you. So I doubt my own self, I doubt those I love who never hurt me, you know? Why?
I guess it comes down to wanting to believe something that has no place in reality,

. But really... .why do I doubt myself? Probably has to do with being a perfectionist, with being hard on myself, with believing that I am responsible... .which has a lot to do with how I grew up and all that. Programmed? Maybe... .habit more likely.
I don't know if these thoughts of mine help you at all but I do hope so... .