Forgiving myself was very, very hard for me. It sure didn't happen all at once, but more in stages as I grew in recovery. It began with accepting that I was human and therefore I should not expect myself to be perfect.
Eckhart Tolle and Deepak Chopra talk a lot about negative self-talk and how harmful and insidious it is. I had to pay attention to the random thoughts running through my mind. I also found journalling to be very helpful in getting rid of the initial anger that I felt towards myself.