BIG HUG
Changing thoughts is the hardest thing to do. Perhaps you should look into meditation. It really does teach you that you can control your thoughts. Most people don't realize that you can do that, but you can. Once you understand that you can control your thoughts, you pay attention to what you are thinking about yourself at all times and when you catch yourself thinking something negative about yourself, stop and replace the thought with something positive about yourself. Changing your thoughts is like water wearing away on a stone. Drip drip drip -- little changes in habit wear new grooves slowly, over time, and change is not immediately apparent. But it will come gradually and you can feel the difference over time, most definitely.
Here is a good non-sectarian book on meditation that might be of interest:
http://www.amazon.com/Minding-Body-Mending-Bantam-Books... Also, many of us, for what-ever reason, think of others in more positive ways than we think of ourselves. We are often harder on ourselves than we are on other people. So when you catch yourself thinking something negative about something you have done, or judging yourself, stop and wonder, "Would I think that about X if he/she did that?" Substitute someone else who you love for X. Most likely you will find you treat others more tenderly than you do yourself. But you are a wonderful wonderful person who deserves just as much (if not more!) tenderness than you give to others!
I think this is your #1 goal to work on in Step 3!
It sounds like your burden is very heavy. Perhaps you should look into professional help, a doctor or psychotherapist, or a spiritual path, or both. In your tender state, though, please be VERY CAREFUL about putting your absolute trust into someone. Go slowly and trust your instincts and your common sense. Don't trust anyone who promises you quick fixes. This work is slow. And don't trust a spiritual path that asks an unreasonable amount of money from you, or unreasonable time commitments. Finding a spiritual home (and a doctor!) should be approached in the same way as buying a car: you should read up on it, take it for a test drive, and make sure to read all the fine print, even if you may feel very drawn to something.
May I recommend a book for you? This work-book is wonderful for those of us who are trying to get into the habit of love and joy:
http://www.amazon.com/Pronoia-Antidote-Paranoia-Conspir... ((( HUG ))) Love and light to you! Never doubt that you are a Buddha and will surely attain enlightenment!