Who Killed Gregor?

Gregor dies at the conclusion of The Metamorphosis. At first, I thought his death was underwhelming in a way. Kafka opens the book by dramatically proclaiming that Gregor had been transformed into a giant insect. It was so absurd that for the first few pages, I wondered if it was only a nightmare. Based on the striking beginning, I initially expected Gregor to go out with a bang.
But, as we read, he dies peacefully in his room, shortly after dawn. His death is only really described in one paragraph. I think the nature of his death reflects what we've been talking about in class; how Gregor is reduced from the breadwinner to nothing more but a nuisance. His death seems almost emotionally insignificant to the family, which reflects how they have lost most, if not all sympathy for Gregor.
In contrast, as Gregor has slowly become this dependent creature, the rest of his family members have each becoming working, contributing members to society. So there's sort of a cycle, or reversal of roles.
I found the last part extremely sad to read. It made me dislike Gregor's family quite a bit. I guess I had a faint dislike for them ever since the beginning, where we saw Gregor groveling at his manager's feet while Gregor's dad was lazily enjoying his giant breakfast. I really disliked the fact that although the father was in debt, the whole family pushed the responsibility onto Gregor. Maybe I don't understand enough about family dynamics during the time period, but it seemed extremely unfair. It also made the family look a little pathetic.
The worst part to read was at the end, when Gregor's family had clearly lost all sympathy for him and decided it best to get rid of him somehow, and Gregor agrees. As he dies, all he thinks about is how he "must disappear", for the sake of his family. Despite how badly he has been treated by the family, especially by his father, Gregor still seems to be loyal and still has their best interests in mind.
This makes me wonder if he in a way, committed suicide. I know it's a bold statement, but by the end, Gregor was quite determined to die, to disappear. Perhaps he willingly lost the will to live (if that makes sense). In addition, most people who commit suicide do it because they feel as if they are a burden on family and friends. Gregor clearly feels this way.
Another way you could see it is that his family killed him. One huge blow was his father's apple throwing. Another was the lack of suitable food. It's possible that Gregor felt like he had no choice but to die, especially considering how weak he was due to his family's neglect.
No matter how you interpret Gregor's death, it's definitely a somber ending to an adventurous story.