Any returns filed now will go into holding in a data warehouse. Only the IRS determines when the returns are downloaded by them from the warehouse (tax providers do not "push" tax returns to the IRS.) There is no way to be sure that a return filed today will be download by the IRS before a return filed by your ex next week.
If your return is rejected because of a duplicate dependent claim (this will usually happen on or after 1/29) you will need to print your returns, sign them, and mail them to the IRS. The IRS will process them as-is and then start an investigation over the summer.
