Oh who so much good stuff in this thread that I'm sorry on I only just found it.
I can relate a lot to your mind being your prison CroMagna, the only help I can provide is to make these voices conciousous. Write them down and review them, to see what they are trying to do and then you can rebutt them or redirect them. (Oh and my father does this to an even worse degree and he is 64!)
A book called Self Esteem has a lot on this topic, most book stores carry it.
But what has helped me the most is Zen and detaching from the negative. As well as observing but not judging the emotions or the source. Sometime the best thing you can do is give yourself time and space to be alone or to put yourself first, like exercise. I think exercise and nutrition is the number one thing that has helped me the last few months. Having a purpose or finding meaning in what your doing will help too. Another book here would be Victor Frankl's Man's Search for Meaning.
Do something, even if you don't feel it, but you know it. Cause sometimes our emotions can lie to us in order to keep us 'safe' in the known.