I guess u must be confused by so many good suggestions below. Here are my 2 cents, if u do not mind.
Apparently u cannot afford the life style ur wife wants. (nobody is right or wrong here). Three possible ways: 1) u improve urself to earn more money. It is not easy, especially for short period. I know many couples work hard TOGETHER to improve their incomes and they also enjoy the whole process. 2) your wife reduces her demanding. Sounds to me, it is not easy. 3) divorce.
Sorry to tell u that i think divorcing is the best way for you right now. U two just simply do not fit each other. I personally will never marry a woman you described in your post. But, hey, in the world, there are many women like her (look at all the posts under ur post), and nothing is wrong with them; they just need to find a person who is already very wealthy. Apparently u r not, at least at this moment (maybe u will be Gates in 10 years), but looks like ur wife does not want wait. Give her freedom and let her find who she really wants. Find a lawyer and protect urself well. U two do not fit each other and you need to protect urself, just like she needs to protect herself as well.
Good luck!