Mortgage default after Ch7 discharged, what is the foreclosure process?

I filed for BK 7 in Oct 12, and was discharged in Jan '13. I did not reaffirm my mortgage, however, I kept paying my 1st and 2nd loans. My house is about $70k underwater. I am now having problem making the monthly payments. After much thought, I decided to just walk away. I stopped paying in May. I read somewhere that per Maryland foreclosure law, if the default occurred after Bankruptcy discharge, that the Lender may petition for immediate foreclosure. What does that mean? The "judicial" process of getting notices, such as Intent to Foreclose, Order to Docket, etc are not applicable, and Request for Mediation is not applicable. Is this right? How long do I have before the eviction notice? I was hoping I get to stay here until Nov/Dec, but it looks like it may have to get out sooner. 90 days? Today (exactly 45 days from my first missed payment), I received a Borrower Response Package from Nationstar. They are giving me until 7/5 to send the completed form + required supporting docs. Should I send by 7/5? Please advise.