You could get casual work such as cleaning, babysitting, gardening, bar work, coaching, decorating, mending, call centre work, working street markets - to supplement your main job. I did all of those when I was 22. People often need some sort of help and if you already have a job then you can provide references.

Your mum sounds like she deals with overwhelm by isolating and sleeping. If you brother tried to kill her (is that correct?) that is serious trauma. She may need years to get over it. That's her challenge. Perhaps she will reconsider about the lease if you give her some space?

You are right to focus on taking care of your own situation. Your mum has done her job to the extent that you have reached adulthood alive! Perhaps you need to each deal with your challenges separately for a while, just keeping your heart open that things may improve at some point in the future.

I feel like you probably needs some peer trauma support - hope you will find that here and/ or in real life. Keep plodding forward, and congratulate yourself at each step! Sometimes that is all that is possible, but you will get through and out the other side.