your accountants were wrong. you needn't to prove

your marriage. no one need to prove marriage on tax return.

W-7 could be filed with passport only. True for sure. I did it before.

your wife's foreign could be excluded through "foreign exclusion" because she is out us for whole year. annual execlusion is around $80,000.

so married jointly + foreign exclusion + w7. you could save a lot of tax! however, you need pay a lot of accountant fee over $300 must.

you'd better amend your tax return.