Returning Member

Work in VA but residences in VA and DC

My permanent home is in DC.  Starting the beginning of this year, my employer transferred me to a two-year Virginia location which is too far to commute.  I have rented an apartment in VA and live there most of the time, surely > 183 days per year.  For tax purposes, how do I handle the two residences, which residence is used as the official filing address, which state should be withholding state taxes and which state tax returns should I be completing?  Thanks.