Rahul:
Yes, file jointly with your wife.
Download Form W-7 from
www.irs.gov, fill it in as required by the instructions and mail the W-7, your tax return (leave your wife's SSN field
blank) and any other documents required by the W-7 instructions to the IRS Center in Philadelphia, Pennsylvania (the address is both on-line at the IRS website and in IRS Pub 519).
The IRS personnel will issue you the ITIN, put it on your tax return and process the return. They will mail you the ITIN so you can then file your state income tax return.