I think everything you have written is very accurate. The truth is that learning to forgive and let go of things that have hurt us is a giant step towards emotional maturity. Sometimes, here in Venezuela, with all the difficulties we go through, it is easy to fall into the trap of carrying resentments and grudges. But as you rightly say, that only hurts ourselves more.
That metaphor of the hand holding an object all day is excellent for describing how exhausting it is to carry those emotional burdens. At the end of the day, we must learn to let go and forgive, not only others, but also ourselves.