You may want to consider getting a divorce so as to insulate yourself against claims that may be made against the marital estate. If he has truly abandoned you and you are unable to locate him, the court "may" allow you to serve him divorce papers by publication in the newspaper, to his last email account, facebook, etc. It is up to the court. By filing now achieving legal service, even if not personal service, you can set up a judgment against him for child support and clear the title to your property.
Check your credit reports, too, and put a flag on your account to ensure that he does not access your credit lines.