Lillith,
I so relate to those feelings. It feels so difficult to change negative beliefs that have become so entrenched over the decades. I'm familiar with mindfulness practice that says "Don't identify with those thoughts", but it's hard not to get sucked in when you're in the swirl of it all.
I've actually felt some relief yesterday and today, after taking more of a stimulant medication for ADD. I felt more motivation and mental energy, for the first time in a long time. Makes me think the neurochemistry is a big piece of the problem, aside from trauma, crazy family, disappointment, etc.