I can relate to your problem. The reason is the mind. We have to work on the mind. The mechanism behind self-hatred is that the mind has locked itself into a loop of shame and guilt about something that it perceives being ‘bad’ or ‘wrong’. It does so because it can’t accept itself as it is, with flaws, evil-doings, and other shortcomings.
Try to see it a little from the outside. It’s just thoughts and emotions spinning around and around in your mind. The problem is that you identify with these thoughts and emotions and call them you. You desperately want it to stop and you struggle to find a solution inside that turmoil of thoughts. From within there you desperately scream ‘stop’ or desperately try to think positively or love yourself. This is not going to work.
What you need to do is to start meditation.
Find a center that shows you how to throw away or let go of your mind. Practice diligently, preferably many times a week. And bit by bit, you will naturally stop hating yourself. The reason why this works is because by emptying the mind, the loop of negativity and the identification with that negativity and pain will gradually stop. Bit by bit, your mind will lose its attachment to that way of thinking, and the negative thoughts will come to an end or at the very least become irrelevant to you.
It may take a month, a year or perhaps even longer. It all depends on how strong your attachment is and how diligently you practice. However, it doesn’t really matter if it takes two weeks or two years. You still have plenty of time to live a peaceful and happy life once it’s taken care of. Because when it’s over, it’s over and it doesn’t come back since the quality of your mind now is different and no longer identifies with those thoughts and emotions.
When you meditate, try to see yourself as honestly as possible. The reason why people suffer from guilt/self-hatred for not being good enough is because of inferiority-based pride. The self wants to be good so badly that it can’t stand being bad. The motor, the core, of that suffering is the pride. Admit that you have this pride and desire to be good within, and bit by bit your mind will accept and come to peace with this aspect of yourself. You will then be fine about being a bad person and that will make the cleansing process easier. Ironically perhaps, being bad thus becomes the path to becoming a truly good person.
Lots of love, and please check out the video below. Acceptance is the key.