Hi Tusphi and welcome;
What a dreadful situation. I can totally understand your worry; I'm so glad you decided to post. The helplessness you must feel would be horrible.
As your brother's been diagnosed, I can see he has support for his MH issues. The fact he's staying on his med's tells me he's also self caring in this respect.
There are options you can take advantage of like the Mental Health Hotline in your state. If you call, they'll help you find avenues to sort thru this mess your brother's created; namely financial support and assessing if he's capable of looking after himself, especially if he's suicidal.
The other is Centrelink. They can refer you to a Social Worker; I believe they have them on staff and may help you make an appt.
Another option if you're in NSW is the new govt program called the NDIS. (National Disability Insurance Scheme) Although there needs to be an application made to qualify, initially they can advise on what's available to suit his needs.
If his situation is as dire as you fear, he needs to be registered as having a MH disability there as well as with Centrelink. (They're separate entities) Without these official 'labels', he'll fall thru the gaps so to speak.
I'm also concerned about you in all this. Helplessness can eat away at people, so it might be a good idea to talk about your situation with your GP. There may be the option of him/her referring you to a psychologist for yourself.
You've done well to find the courage to post here so good on you! Keep writing because as we've all learned, talking about our concerns with others who understand is completely therapeutic.
Drop in anytime ok. I'd love to know how things pan out as well as chat; you obviously need to purge some of that angst and worry hun. I'm in your corner and will help any way I can. You're a good person indeed...