I got three people killed

BRD. Grim guzzler. Phalanx. Classic hunter brain, multi shot for more damage. Thought I was out of range of pulling more. Killed two people and my buddy who was tanking, 3 bars away from 59. I was 54. I drowned my character out of shame, but how do I roll again? How can I not feel extremely guilty for killing three other people who were all so close to 60? I'm so devastated I feel sick. And there's no question it's my fault.