I have been in your exact situation, and although this feels like it's the end of the world and you're a dead man walking - you aren't. You are likely to be more fine with respect to your academic standing than you realise (unless my experience of the APC was the exception and not the rule).
Firstly, I hope you feel better about yourself. You are important and deserve to love yourself. I know what a kick in the guts this is. When I first received the letter, I know I thought to myself "oh great, confirmation that I'm a fucking failure".
Thankfully, my experience was that the APC is very compassionate and understanding.
My situation was that I went from being on a scholarship and maintaining a 90 average in my first 2 years to failing out of the course by 4th year.
I actually fronted the panel twice. Once when I was undiagnosed, and thought it was simply stress and taking on too many things at once.
At my first hearing, they asked me what my plan was to alleviate my stress. I explained that I was going to try to organise my time better, and drop to a lighter study load in order to give myself the best possible chance to succeed. They agreed this was a good course of action, and specifically noted in light of my past results that I should be allowed a second chance.
Unfortunately, it wasn't as easy as that for me. I continued to fail subjects after the first hearing, and finally had a huge breakdown after which I sought help and was diagnosed with clinical depression.
At my 2nd hearing two years later, with the appropriate documentation to support my diagnosis, the panel allowed me to continue my studies and were extremely kind and understanding.
Don't be afraid to be open or vulnerable. They're not there to yell at you - they genuinely are trying to ascertain if you should still be studying. If you simply want to remain in the course, they are very likely to give you another chance.
They will ask you to develop a plan detailing how you intend to overcome the obstacles you are facing, potentially including academic counselling and a written statement of your plan.
I had no documentation for the first hearing other than my own written explanation of stress. For my 2nd hearing I had a letter from my Psychiatrist detailing my diagnosis and treatment. I would definitely advise that you bring any relevant medical certificates detailing your history with mental illness as it is a very important factor.
If I recall correctly, medical documentation would have to have been submitted a few weeks ago. It's very important that you contact the administrative contact on the warning letter immediately to get an extension on that submission date if this is the case. If their policy/procedure has changed since then, please disregard this advice. The student rights officer will have the most helpful advice on this matter.
The student rights officer will explain what they can and help you to build your case, but ultimately I found that they don't exactly need to kick goals for you in order for the APC to look favourably on your case. In my case, I barely consulted the service. I will say it is nice to see a friendly, supportive face on the day, and I still remember that feeling even now.
Mental illness is a hell I would not wish on anybody. Please take care of yourself and continue to seek professional help. I am unsure if they are allowed to do it, but the APC may ask you to seek counselling and I would certainly advise that you do it. Best of luck, and please feel better about yourself.
Regarding your financial issues, you should use this website to locate free services that can help you get your debt under control.
https://www.moneysmart.gov.au/managing-your-money/managing-debts/financial-counselling