Will the IRS force my husband to amend his return?

I just found out my soon to be ex husband filed Married Separately, Standard Deduction, and already received his refund.  I filed an extension and am preparing to file MS, Itemized (to document my small business startup and capital investments).  He refuses to discuss amending his return and filing jointly or itemizing, as he doesn't understand business write-offs and thinks I'm trying to put one over on him.  My business made $9500, while generating $11,000 in write-offs, but I paid no taxes and am getting no refund as a result.