Why isn't my mind as forgiving as my body?

I cut my finger when I was using a trimming knife. It was only a small cut, and it healed completely in a few days. Yet I had thoughts about how careless I had been for much longer. My body has also healed with time from some bigger injuries. A broken bone was healed in a few months yet some things that my mother did, I had not forgiven her for over half a century. Just little things like not giving me the sort of sandwiches that other boys enjoyed in their school lunches. I didn't take responsibility for doing anything about changing the situation at the time. I was acting as a victim. I never said anything to her about it. I could have requested something different from my mum. Or at school I could have swapped a sandwich or two. I chose to blame her instead for my not enjoying my lunch times. I could have healed my pain much earlier in my life. She hated wastefulness. To throw out perfectly good bread just because it was not fresh would have been inconsistent with her values. I could have acknowledged her before she died for being true to her values. I could have forgiven her for not giving me the luxury of really tasty lunches. By forgiving her earlier in life I could have freed myself to enjoy more little luxuries in my own life. I can forgive myself for discarding stale bread!