it seems you did not live in the home two out of the five years before sale. Thus you will not qualify for the home sale exclusion. the questions you did not answer are - is your name on the mortgage and what happens when you sell. if your name remains on it, seek legal guidance before completing the sale. should something happen, even though you ex will be the only owner, it's possible the mortgage company could come after you.
you should get 1/2 the Fair Value. against this you would get 1/2 the basis. your gain, taxed as long term capital gain, will be what you get less your basis.
