It's A Real Mess I'm In

I got a real estate broker to sell my home in May 07, He had a buyer & had me sign a Quit claim deed to her. I received a portion of the money due me at that time & the remainder was to be given at the closing, which was to be in Aug 07. as per the contract. He has a section 8 renter living in the home,since June07, for which he is collecting rent monthly. Now he tells me the buyer wants out & he need to find a new buyer, so I am left hanging. My name is still on the mortgage(which he has been paying, but he pays it late & this is being reflected on my credit report). Yet since I signed the Quit Claim deed he says I am nolonger the owner & so he does not have to dis-close any information regarding the sale to me. I know he is trying to sell the house for more than the original contract states because I had someone call & inquire about a purchase. At this point I just want the rest of my money & my name off the mortgage, but I feel that with the housing mkt as it is, a higher priced house will take longer to sell & of course there the matter of the sec 8 renter. After he pays the monthly mtg he pockets a tidy little sum.
I just want this over!! What do I do?