Hi cardooney.
Like some others here, I also suffer from some of the same self-degrading thoughts as you. Had them most of my life, and a feeling of ineptitude was always prevalent. It took my life exploding and the help of a therapist to become aware of what I was doing, to myself.
It sounds cliché, but loving yourself is the backbone to eradicating these self-sabotaging thoughts (that can lead to actions).
Loving myself is hard, for reasons long gone and through memories faded..but bit by bit I am discovering the real person that isn’t crippled by doubt and fear, and I am slowly falling in love with him.
In my experience, you can find love when you make yourself proud, mostly when you are proud of doing something you enjoy, like to do. I realized my work does not fulfill me, it isn’t a very big source of pride, but many other things closer to my heart are, and there I find myself more and more these days.
It’s by no means a smooth road, full of setbacks, reversions and newly discovered hurdles, but once you decide to set out on it you just keep walking.

I’ve read some of your poetry, it beautiful, and did not come from the mind of an idiot.
I end up talking about myself a lot but I do it in the hopes that it may strike a chord, that and I cannot speak for anyone else.
A reason I put up with my self-sabotage for so long is that I was terrified of the alternative. Success, recognition, attention, or in cases where there was disagreement, I feared confrontation. I found myself agreeing to things that went against the warnings from my body and the lamentations of my mind.
Ugh, I hated myself for being that way, for so many years..there is still residual disdain held there but also sympathy and a growing compassion.
I really didn’t know any better and life is linear, regrets are foolish.

My advice, and as others advised already, find a nice therapist and start walking.