Quoting [P&T's Mama]- Baking#3:" Mama tosilas please explain the difference. I have two w2 's futon my jobs I had prior to mid Aug. But I no longer work and haven't since then"
You cannot file together because you are not married. You have to file your taxes seperately than his. So that shouldn't even be a question.
If he supported you and your child for more than half the year then he can claim you and your child as a dependent.
Here's more info on if you qualify for him to claim you as a dependent