Help

I live with my brother and his partner. They have a 15 month old toddler who is at that stage of touching everything. What’s frustrating is that his mother buys him a new toy every week when we already have HUGE amounts lying around everywhere. Also she doesn’t clean up after him so everything is left lying around and the house is a mess. I think she has ADHD cause she gets extremely excitable when she talking about getting a new toy for her son. Her partner (my brother) doesn’t have the balls to tell her no! So she just does whatever she wants and the house is disgusting. What can I do?? Its exhausting being the only one cleaning up and im afraid if I speak up to my brothers gf, il get kicked out!