So, I just found out that he had multiple tumours on his brain and neck and this is what someone very close to him said today: "He had to hate the way he was feeling, but he had 2 to 6 months to live according to his doctor. They brought him a morphine kit. He nodded off at the Rainbow and never woke up again."
Looks like Lemmy overdosed on the morphine he was self-administering to himself because the pain had gotten to bad. His speech had become slurred and he needed a cane to walk to the bathroom. So yes, it was Lemmy who ended it, but his end was coming anyway. Sad.