I feel that our energy is determined by our intention. You didn't intend for that to happen. I won't tell you some platitude like don't blame yourself because I personally can relate to situations where my actions had horrible unintended consequences, and I understand that we are our own worst critics and juries. I hope you find comfort and a way to honor her memory in your day to day life. I imagine she would've wished the same for you and would understand that it was just boys being boys, not some sinister plan to hurt her. Best of luck man