Hi redshift,
I had a terrible time coming to grips with the person I had become. There was so much guilt and shame. I came here, asking the same question you did and the answer I got, from a wonderful lady here at SR, was to journal. Oh, but I really didn't want to do that. I didn't want to see the words written down on paper. But, I was desparate and so I began. Everytime, I had a dark thought, a specific memory, I would stop and write it down in my journal. And, the memory would fade and lose its power. It took me a long time, nearly a year of writing, to get it all out. But, it helped a lot. And, in the end, I burned the journal. Forgiving yourself is so hard to do, but it is a gift you need to give yourself.