Single mother moved to US in 07 came back 12/08 I need help

Ok here goes. I moved to US 04/07. Was a single mom. My son was turning 18 in August of 07. I was on EI for first time in my adult life (I am 42 now). Had a chance to go find a job down to US on a resident card, went for it meant more pay for me and my kids.
In retrospect, If I knew then what I know now. But i need help now. if any is available.
I was receiving EI went for interviews in 07 came back twice in 07 then money ran out got stuck there. EI sent me letter stating i could not receive EI while in US. I explained that I was looking for job. Sent then job search info. Sent them everything to no avail. I have to pay back what they gave me.
Came back in 12/08. Revenue Canada wants me to pay back taxes, GST credit, AB Family tax credit. Child Tax Credit. Everything. I am up to my ears in debt to RC.
Can anyone tell me please if they have found themselves in this situation and is there any way for me to reduce the debt to them or is this it? That I will owe them everything.
Has anyone been in this situation? Any help would be greatly appreciated.

Thank you!

Declare yourself non-resident for the period you were in the US. That simple really. They can't say you were resident if you have a permanent resident alien card for the US and lived in the US.