I'm not quite sure I understand what you are asking. Most generally it is advantageous for a married couple to file jointly. You each get an exemption, just as there is an exemption for each child. So I am not understanding how/why he would claim you as a dependent or no longer be able to claim you as a dependent.
Lets say that you throw your income and his income into the pot, pull out the appropriate deductions and end up with an adjusted gross income of $50,000. Married filing jointly you would pay $1785 + 15% of anything over $17,800 or a total of about $6615. Now if only $1000 of that is yours, that means $49,000 of it is his and married filing separately you would probably pay $0 while he would get to pay $4,991.25 plus 25% of the amount over $36,250 or a total of about $8179.
So unless there is some compelling reason, file jointly.