Holding on to resentments is like setting yourself on fire and hoping the person chokes on the smoke.
Letting go of those resentments means you love yourself more. All that bitterness and anger just builds up and does nothing but harm. Plus the person you are holding that grudge against either doesn’t know or doesn’t care. Love yourself enough to move on with your life.
Life is 10% what happens to us and 90% how you react to it. You control your reactions. You can’t control others.