Sister in law issues, how do I handle them?

For context I've known my sister in law (her 35, married to my brother) since middle school.. I'm 32.

Sadly we BOTH have had hard times hit us just in the past 2 months. I lost my job, got to a car accident and have been struggling with depression and finding a job. She has lost her father to suicide, had to put her mom into assisted living and recently had a mild surgery that restricts her diet and hates left her very touchy since she loves fatty foods and cannot have any.

Note: I was living with her father but unfortunately he committed suicide and since I lost my job I had no option but to move in with her and my brother.

They have 3 cats and I have 2. But we are slowly introducing them and it's going very well for 4 of the 5 cats. But one of their make cats is stressed out about the situation and is peeing in random spots around the house. My 2 cats are in my room 24/7 until they can calm the cat and get him used to mine. One of my cats has started getting ants in her pants and wishes to explore the home. I told my brother that perhaps SOON we should put my cat into a new room on her own to explore for a bit. Well my brother passed along this info to my sister in law and she EXPLODED. Shouting about how I'm rushing things and that her cat is too stressed out and that she is handling everything on her own (even though my brother has literally done all the work so far) and was obviously pissed. My issue is I cannot address any of my concerns or wishes without her going off about something wrong with my requests. Or she'll send my brother to talk to me. She's been like this since I've known her but I have only been living here for about 3 weeks and I'm already starting to want to barricade myself into my room to avoid conflict. (Trick I've taught myself at young age, emotionally abusive mother blah blah blah) If I try to talk to her I'll know she will get to defensive and make the situation about her even though she's not the only one struggling financially and emotionally. And yes I'm getting unemployment and able to pay my own bills and rent but still struggling to find a job.

What should I do? My brother would not do anything about it because I love my sister in law but she's a bit controlling of my brother and wouldn't like it if he defended me at all.

All I can think about it just finding a good steady job and moving out asap.