I’m a kid and need advice (this is long btw)

So my moms going through her second divorce and this is so much different from the first one that was with my dad. The one with my dad was on good terms and it was a mutual agreement, this one however is completely the opposite. So my ex stepdad was emotionally abusive and narcissistic, also really manipulative. When we finally left about a year ago he basically stalked us. Saying things like I’ll make you come back, you’ll pay for leaving, I can change, and stuff like that. My little brother is his and my moms kid. Now this is where it’s getting really hard...my mom can’t work enough to get us a house, she has a chronic illness, so we are living with my grandparents. She is barely making 20 bucks a month, luckily we have child support from my dad, he is super good about it and pays what he needs to every month. My ex stepdad on the other hand barely pays anything. He’s supposed to pay 500 a month but only pays 100, he knows my mom can’t work and basically rubs it in our face that if we would’ve stayed we wouldn’t be in this situation....I just really feel like I need to get a job to help support the house hold but I’m to young to get hired anywhere, any advice?