The only tax status is "single", "married filing separately", "married filing jointly" or "head of household."
To file as "single" while still legally married, requires that you be "considered unmarried" for tax purposes. This is a matter for state law, but a legal separation, before the divorce is final, almost never qualifies you to file as single or "unmarried."
As above, please take your divorce paperwork to a qualified accountant. You may need to report part of your ex-spouse's income as taxable income on your tax return. This is not something to guess about.
