Child tax credit and child support garnishment

My husband has his income tax refund garnished for arrears. We had a child last year and want to claim our child tax credit but dont want it to be garnished. What would be the better option to file separately on the same return and I claim the child tax credit or file jointly and file an injured spouse form. The only thing is with the injured spouse form if we jointly claim the child tax credit how do they decide what gets garnished do they take half and give me half?