How much income, if any, did you have? Did you and the children all live with your boyfriend the entire year? Is the child's other parent in the picture?

i had less than $2000. Yes, we lived with him all year, and no the other parent has no right to claim per divorce decree.

Your boyfriend can claim all of you as dependents on his tax return. None of you can be claimed as qualifying child dependents since none of you are actually related to him but can be claimed as unrelated qualifying relative dependents. You cannot file a return and claim your children if he claims them.