Elderly parent being taken advantage of and not sure what to do?

I have on brother that has been taking advantage of our parents for years. He is in his 40's, never worked, and spends most of his time smoking pot and playing video games on our parents dime. Unfortunately, the last few years my father started suffering losing his memory and sometimes not always clear (I think the Dr. said early stages of dementia) and unknown to us at the time our brother took out credit cards in dads name. Like I said its always been a struggle in the family wanting him to not leech off our parents who should not be working at 80 and 90 years old to support their 40 yr old kid. But Mom always defended him and dad turned the other way.

Our dad recently passed away at 94 yrs old. He took care of the finances or "thought" our brother did. Now we are trying to help mom since she never knew what bills to pay because dad always did it. However we have uncovered a HUGE mess. They are behind on all their bills. And they have about $40K in credit card debt (mostly accrued in the last 2-3 yrs, we suspect our brother took these out without our parents knowledge). Mom didn't seem to understand where the credit cards came from, but when we brought up having them looked into for Fraud she quickly shot us down. We also found a NEW card with video game purchases on it of about $1000 that was done while our dad was dying in the hospital. Its all very upsetting. But our mom defends our brother and will not put any responsibility on him saying she gave him permission (when we all know she didn't because she was surprised as the rest of us at the new console after returning from the hospital).

Dads retirement was their main income, and now with so much debt, and no income, mom is probably going to lose the house. But we cannot convince her to cut ties with our brother and move in with one of us.

We just don't know what to do and feel helpless after our father just passed and our mother is about to be broke and homeless thanks to our brother.

But we don't feel like APS will do anything because she will take all the blame and insist he never did anything wrong. :0/

Any advice??

We (me and my other siblings) do not have any kind of POA and are still looking for the will to see if dad had any of us listed to be able to control the estate. But the outlook is not good.