Need somewhere to vent & this is the only place I actually can.

Okay so we currently live with my MIL. (I'm only 18 & my bf is 20) we have been looking for our own place. But every time our baby is asleep (9 mo) she tries to be as loud as she possibly can. (he's 1 yr & she's 25) we've talked to her about it but she doesn't care. She let's her kid run off and do whatever he wants, goes through our personal stuff. He hits my kid and does nothing about it & He's a real cry baby, if he doesn't get his way he throws a tantrum. And I'm not kidding when I say he's a cry baby. You touch him and he starts to cry. Any advice on what else we can do!?