Spousal support IS alimony. it is the modern term that is now more politically correct.
1. the old term alimony was a right and expectation for women in divorce, however, now
2. Alimony is not a guarantee because many women are careerists, and
3. men can now get alimony,
AND so the courts now call alimony, spousal support.
The person who pays spousal support can claim it as a deduction, and in that case, you have to claim it as income.
He can not say that you will be audited....he does not know that, so he is scaring you.
But, the IRS can send out a letter to you or they may at some point get a trigger for audit if they notice him claiming the deduction and you not reporting it as income.
AND your ex has no idea how the IRS will treat it, or how much you would pay in fines, interest and penalties. The IRS, contrary to popular belief does not work that way.
If he reported it as a deduction, the more likely scenario is that you would get a letter inquiry and be given a chance to claim it.
NOW, how much to claim. You and your husband need to be clear on this.
You need to get the copy of the divorce decree and figure out if the decree has language that shows how he figured or how much is from child support. You would only claim the portion that is spouse support only and not child support. you can exclude the amounts indicated for that.
in the absence of guidance, then divide the spousal support by the children and you, and claim only your share.
I did note that you were not yet divorced, so instead of a decree, you need to get ahold of the person or office that ordered the support to see how it is broken down.