horror, i think it's based on the amityville house?

Hello... I know this is gonna sound stupid. But a long time ago, I read a bit of a book similarly to The Amityville Horror book but it was a boy in the family that went crazy. I recall him doing something with a shovel and being really weird and solemn? I dunno, I just really need to find this book, and the other books I saw have nothing similar to what I remember... can someone help? Oh, yeah, it's also pretty thick and creepy looking, if I recall correctly.

Please help if you know (maybe I'm crazy)

I think there are a few books in the Amityville series, so could it be one of those?

The Amityville Horror

The Amityville Horror Part II

Amityville: The Final Chapter

Amityville: The Evil Escapes

Amityville: The Horror Returns

Amityville: The Nightmare Continues

Murder in Amityville

The Amityville Curse

The Secret of Amityville

Mentally Ill In Amityville