my ex has decided to stop paying me bc our 16 spends the majority of her time at his house. Can he stop paying?

If there is an existing court order settng child support (by order or in a Final Judgment), your ex cannot stop paying without modifying the court order or Final Judgment.  Every month he does not pay you, he accumulates more arrears. If he does file for a modification of both the timesharing to seek majority time with your daughter, and for modification of child support due to the fact she now lives with him, going forward he will be likely successful based on your inquiry. Will you have to pay some child support? That depends on the relative incomes of you and the ex and the amount of time your daughter spends with each of you. This can be calculated using Florida's Child Support Guidelines (CHapter 61.30, F.S.).  Due to the great disparity in incomes between you and your ex, you may still be entiteld to some child support, just a reduced amount.   You will need to consult local family law counsel in your area to explore the above in greater detail. Good luck!