since you are not married, you each file as 'single'. regardless of who supported whom financially, he claims his child and you claim yours.
the critical on the dependents is that there is a blood relationship and without the marriage certificate, there isn't one. Without that marriage certificate, the IRS doesn't see you as 'the same household' (once you are married, you would normally file joint and since each child is blood to one of the parents, then they are both dependents on the joint return)
