Partha,
1) do not feel bad. This message board is FULL of people who made the same mistake you did. There is no shame in it here. We all know exactly how this happens...the big stories told by the salespeople, the excitement of feeling like you "own" your vacations for the rest of your life....etc. You are not alone. If you hang around here and read the forums, you will see many of these stories.
2) As has been posted above, it is very unlikely you will be able to "offload" this purchase to anyone else for the amount that you owe (some would say impossible). It is also unlikely you could collect enough on the rental market to cover your annual costs (however, perhaps you could let us know what you're paying monthly to cover your loan as well as your maintenance fees?).
3) Whatever you do, DO NOT pay any company that claims they can get you out of your timeshare. These companies prey on people desperate to get away and are scum lower than timeshare salespeople. Just again reiterating the advice of
@LannyPC
4) If you choose to default, do your research. While some have posted there is a chance in certain jurisdictions that have an anti-deficiency law, you may need to seek some legal advice or creditor advice to confirm. I'm hoping someone else can post to some free or low cost resources. If not, check out CreditBoards where there is a wealth of resources posted. They may not be timeshare specific, but at the very least you should be able to get some thoughts on mortgage defaults. As has been posted, you'll likely be on the hook for both a mortgage default (for the loan you took out on the timeshare) and a maintenance fee default (for the amount of maintenance fees you owe each year). Regardless, this is likely to impact your credit.
5) Even if you have to accept a hit on your credit, you can recover. These things fade away over time. CreditBoards is also a good place to discuss how to minimize the impact and steps you can take to recover as quickly as possible.
Best of luck and do keep us posted. It's valuable for us all to see how these things play out...and you will not be the last for this to happen to. Someone else will benefit from your journey as well.