When faced with a situation in which you're living with a depressed elder who verbally abuses, Is it best to stay or leave?

So, here's my story. I've never done this before, but I figure I'd appreciate outside advice.
First, I moved out of my own abusive and controlling family home. I used to keep furniture in front of my door just so I'd feel safe from my mother when I sleep. Good news: I left a bad part of my life. The bad news: I moved into my years-long boyfriend's family home, which consist of him, his mother, and his 82-year old bedridden grandmother.
His mother, 60yrs old, has taken care of her mother on a consistent hourly basis since she was around my age. about 20. She's had a verbally abusive life, from her mother and her ex-husbands in the past. She's passed it on to her son. Her son, my boyfriend, is sweet, silly, and in no means violent and never raises his voice. Not a lot of things bother him. Me, on the other hand, I grew up in a angry household. So when I move out of one to move again into ANOTHER one, I'm at a state of stress that's hindering my college studies.
Why? Because Aida, my boyfriend's mother, knows how to complain for hours and hours. About what? cleaning hands, not cleaning correctly, yelling about certain ways to use things, victimizing herself consistently because of her depression, calling me and my boyfriend 10 times out of the day and 5 more times if she needs something, and just to warn about the weather or traffic or an ongoing shopping list everyday. She's extremely imposing. And if any one of us tries to talk to her about it and figure a solution where we can all have decent space and peace, she blows up into a round of screaming involving victimizing herself again; about how her son is abusing her and trying to take control of her and her life, how she has no say in anything, how she cleans the house and cooks and she's still being treated like she's nothing, how she has to take care of her elderly mother everyday and how we wont survive on our own once she passes away. Ongoing arguments ensue. And it's only so long that my boyfriend and I can go through the immense amount of negative energy and emotional stress every single day.
The only reason I've still stayed is because I can't get a job no matter how many places I've applied to in person and online and I'm usually busy with homework, studying, and tests for college.

I have nothing against Aida. I understand her behavior and I somewhat understand why she's so stressed and the additional stress that comes from being a senior who's too busy taking care of another senior to take care of her own health. But she won't, in any way, decrease her stress. She doesn't trust any outside help to take care of her mother and her worst fear is a senior home. I brought a tiny chihuahua to her since she loves dogs and to help her decrease stress. She fell in love with it, but the dog is only adapting to her unhealthy habits, which include staying inside all day, without sunlight, and no exercise. When she's complaining on a daily basis, on a screeching level, I stay quiet, because talking things out (as my boyfriend has tried doing) only makes her yell louder. So, instead of decreasing her stress, she just has more things to add on her list of woes. This consistent circle of stress and messy useless arguments is taking a toll on all of us, but it doesn't seem to change and I've lived here for 5 months now.

Is it best for me to stay and endure it? Or is there an alternative? Or a better way to handle this?