Your ex-husband (the giver) should be filling out Form 709, not you (the recipient).
Since your ex-husband gave gifts totaling $35,000, he would be taxed on the amount over the exclusion $15,000 for each recipient.
The tax should calculate and appear on Form 709, line 6. However, there should also be a credit for the same amount on line 12 if the donor has not exceeded the exemption.
