Past does not indicate future. No matter how bad your past could be your present problems are being caused by your thought process that u have now. U just have to change it and u will be all good. Medical science cannot erase past but it can councel u to improve ur present and future by changing ur thought process. Once u see things with this new thought process u will not irrationally think about ur past. U can refer a cognitive behavior therapist or can go for self help online.