Even if AA is not your method of choice for recovery, get your hands on a really good Step book. I agree that steps 4-9 deal specifically with what you are asking. I didn't believe it myself for a long time--I do not attend AA meetings but do attend another 12 step group meetings rather inconsistently. Something clicked inside of me just a couple of days ago when I was literally riddled with guilt, regret, anxiety et al....I realized the answers were in those steps. Especially #4. I bought a workbook and it just flowed out of me! I am seeing the magic.
Anyway--don't be so hard on yourself! Here's a quote I read--don't know who to credit it to--but it is in response to someone judging someone else:
"If her past were your past, her pain your pain, her level of consciousness your level of consciousness, you would think and act exactly as she does. When your realize this, you will have forgiveness, compassion and peace."
Maybe give YOURSELF this compassion they mention. You did the best you could with where you were at the time. Forward!