why kakashi killed rin

The death of Rin is known to have an impact on Kakashi as he developed what is known to be PTSD orpost-traumatic stress disorder which happened after the death of Rin in the unfortunate hand of his. kakashi sharingan eye Rin’s death has caused nightmares in his sleep as he is reminded of her death and how she died in his arms. ao no exorcist rin and yukio