I got a 1099-S from the sale of my home following my divorce; my ex and I split the proceeds 50/50. How do we file with just one 1099-S listing the full gross proceeds?

We need to each be able to submit half of the gross proceeds, but only I received the form I think because the mortgage was under my name. The total proceeds is over 250K so I need to not be responsible for his share of the gains tax.