May I file taxes separately even when the divorce is not settled yet?

Hi, I have separated recently from my husband in August 2008 and we have filed jointly because we were married for 4 years. This year he has called me now that he knows the taxes are close by to ask me to send him my W2 form. I do not want to file with him, since I am going now to college and do not want to depend on him on anything that I do. I have 2 kids and I am the one supporting them, he sends the babies money whenever he wants to. He used several excuses as to why I should file with him, for example that I will not be able to file individually because I am still married, or that child support issue which I am not interested in because I fully support my kids. He has a business and I know that if I decide to file separately it will mess up his taxes, but I want the tax money to complete my divorce. Please any answers you provide will be deeply appreciated.