Unfortunately, under the law your mother has no legal rights.  Even though this man has not lived with his wife for years, she still is his wife in the eyes of the law.  In fact, the hospital risks a lawsuit if they do not recognize her rights.  Unless there was a written document, such as a Medical Power of Attorney or Living Will, etc, your mom really isn't going to have any say over this man's medical treatment.Note:  TX does recognize common-law marriage, but not if 1 of the parties is already married to someone else.