I used to have severe low self esteem, that crippled my social life. To quote Black Manta, self-esteem has a lot to do with other people. We seem to need our self worth validated by others. Not everyone needs this of course, but many of us do. And when we grow up not receiving enough of this validation, or the opposite (bullying, being insulted, comparing self to others etc), we develop low self esteem.
Some things that helped me was changing my job to become a teacher and volunteering. Knowing that my actions can make a difference in an animal's life or a child's life makes me feel valuable. I also dropped toxic people and only engage with people who treate me with respect and kindness.
I wouldn't say I'm completely confident now, but I think to truly develop a better self esteem, one needs to surpass needing this validation from others. It sort of has to come from inside you, this sense that you're of value, regardless of what society/individuals say/think. What helped me the most was meditation and yoga. With yoga, I came to appreciate my body and with meditation, I guess I looked within and not beyond. It's like people and their opinions matter less and less each day.
But before you can even work on your self esteem, you have to rid yourself of self hatred. Why do you hate yourself? Have you done something so terribly unforgivable? If it not, if you've made less extreme mistakes, can you make amends? Or if it's stuff about you that you don't like, could you list them out and change them one by one?
I'm not sure if any of this helps, but I do hope you feel better about yourself soon.