AITA for controlling my older brother with water

I (17 M) have a severly autistic sibling (20 M). He is bearly verbal (only comunicates in nods grunts and screams), has a unrational fear of water, the dark and being alone and I constantly have to baby sit him.

I have been "locking" him in a croner of the bathroom by placing waterbowls and buckets around him and every time i hear him i spray him with a supersoaker. This has finally given me time alone which i use to study for school as my parents both work nightshifts so they can care for him at the day and i take care of him during the evening/night.

I dont do this because i hate him (which i do btw) but i need time alone so i think its justified, but one of my friends said its bad that i leave him like this for hours just so i can sleep well or get good grades.

So AITA