Dividing line between MG and YA

IMO MG readers want something that is essentially fun, whereas YA audiences are far more accepting of dark stories. You could adapt The Road to YA audiences, I do not think you could adapt it to MG audiences without gutting the story.

You could adapt Assassin's Apprentice to MG, but I do not think you could adapt GoT successfully.

I think it's easier to make the character a year or two older than to make the plot a year or two lighter. Can you age up the MC? The plot sure sounds YA to me.

Your description seems very YA. MG are for ages 9-11 | Grades 3-6. That is a very sensitive age for children (and for parents and teachers that overlook what a child is reading). While there is violence in MG to build suspense it's usually suggested and not graphic.

It doesn't sound like MG to me. The themes seem too dark. It might not even be YA. You'll have to get beta readers to tell you where they think the story fits. Protagonist age is not the sole determining factor of a book's age category.