If I get married, can I add my husband to the title of my property and claim the additional $250,000 capital gains tax exemption for my new husband? 

No, both spouses must meet the two-out-of-the-five years occupancy test.  Your husband must have lived in the home with you for up to two full years, however, only one spouse needs to be on title to the property to claim the full exemption so you do not need to change the title to your property.