In joint tenancy, if 1 tenant conveys his or her interest (or a portion thereof) to another person, the joint tenancy is broken and all of the owners become tenants in common. Additionally, my research suggests that in CA, if a couple divorces and the ex-spouses still own the property as joint tenants, the divorce serves to change the joint tenancy title to tenancy in common.That having been said, it appears that you still own 1/2 of the property; your ex's share is split with his new wife. To be certain of your rights, however, you should consult directly with a local real estate attorney. They can best advise you further.