Lahshmi, I'm sorry to read of your problem. What should be nothing more than a bit of harmless fun has turned into a nightmare for you. Those who are criticising you should reflect a moment or two on how flawlessly they live their lives. The truth is, we all do questionable things from time to time, and 99% of the time, nothing bad happens; we just think to ourselves "Hmmmmm, that was silly, thank god nothing happened!" In your case, the 1% fell on your head, and it could have embarrassing consequences if you don't do some damage limitation.
First of all, follow the advice already given and contact facebook and the police. This miserable worm of a "man" will be taken off facebook, and if there's evidence, the law may be used to bring a prosecution (it would in UK, where cyber crime is taken very seriously). Change your email account, and close the old account; or at the very least, add his email address in gmail spam filter; though he may simply send you mail from a different email id. Hence why I advise you to change your email id.
Whether you "confess all" to your family, well, that's up to you. The fast moving pace of facebook means that you will quickly disappear from the sreens of everyone else's PC and laptops and mobile phones. However, guilty secrets have a nasty habit of coming to light at the worst moment, so please think carefully before making a decision either way.
Finally,, never give anyone your pictures unless you really know them. You can have the sexiest or most depraved chats if that gives you a thrill,, but the moment you identify yourself, with a picture, you put a face to the words, and yourself at risk. I made your mistake a few years ago, and as a result I was branded by a lot of "so called" friends. I closed my facebook account,, and since then, I've steered clear of most social media. I had a lot of fun on line, and made some sexy friends that I still see regularly, but I did suffer some very unpleasant consequences. I hope you can avoid my fate!!!