you said title is your name so you own it and the gain is yours. the mortgage has nothing to do with gain.
if your or your spouse own it for 2 years out of 5 years before sale and you and your spouse occupied it for 2 out of 5 years before the sale you can exclude up to $500,000 of gain. if only one of you meets the 2 out of 5 occupancy test you can exclude $250,000.
