We went to a restaurant last week and i really felt it where everybody was staring,he also commented on the waiter giving so much attention that he got angry and said I'm going to give your number to him  

This is just my view - but the comment above caused me concern. It sounds like it was a fairly simple social occasion but he shouldn't get angry just because you got some attention and became nervous. If he cant reassure you and handle that he's definitely not going to able to deal with a complicated social situation like a party with lots of his colleagues and friends. Also, it would concern me that he's getting everyone busily talking about the appearance of his previously 'secret' girlfriend. That's very un necessary and very indiscreet. It sounds a lot like he's enjoying the drama...  

I think some men can handle being out with an Escort in a social setting and some just cant - and if he cant be relaxed and 'man of the world' enough to be confident and discreet and to handle anything that might happen with good grace and charm then there's no way I would go to this big occasion with him.

Lastly, if anyone threatened to 'Out' me for any reason at all I'd refuse to see them again. The fact he made the threat in reaction to the attention of a single waiter would leave me worried sick as to what he might do once you had to face the mass interrogation and scrutiny of all his friends and business colleagues. Personally, I'd pass on the dress and any amount of money - and stay home and watch X Factor in comfort!

Hope it works out, whatever you decide to do!
R xx