Narcissistic abuse and obsessional thoughts

I've dealt with two narcissistic family members (sister and mother) over a number of years and am well aware of how adept these people are at manipulating and discrediting their victim, even one narcissist (sister) was completely fooled by the other narcissist (mother), but perhaps that's a part of what makes them tick, the narcissist refusing to recognise anyone else's opinion might be valid and having to always be 'right'. As if it isn't enough to to cope all the faults we routinely get accused of by others. In the case of one professional I went to seeking help for stress and anxiety, I was diagnosed with a 'persecution complex' about the narcissist (mother). I also struggle greatly with feelings of inadequacy because the relentless pressure of the narcissist (in this case two)and their ability to push my buttons on issues they know affect me like self esteem and abandonment makes me feel weak and pathetic when I'd like to feel strong and more able to cope.

I find I obsess over this to the degree that its really affecting my life in a negative way. I have a bad case of the 'what if's' I guess, what if I'd been stronger and not allowed their rubbish to erode my self-confidence instead of being afraid or unable to defend myself, what if I'd done something differently that would make someone believe me over them etc. It's like I blame myself in a way. I need to find ways to stop punishing myself for something that I know intellectually isn't my really fault, but wouldn't know where to begin. Any advice would be greatly appreciated. Thank you.