Throughout the US, a person can be married to only one person at a time, whether by following the statutory procedures or by common law. If you are still legally married to your first husband, you cannot be married to anyone else simply by living with that person.
Most police officers are not lawyers. What the police officers likely were trying to tell you is that they aren't in a position to determine the property rights between you and your boyfriend. The police will not get involve in your property and custody disputes unless there is a court order.
Until there is a court order stating otherwise, both parents have equal rights to their children.
You likely will need to go to court to get court orders regarding your property and custody of your son.
You can check the website of AL LegalHelp to see if there is any information useful to you. The website is: http://www.lawhelp.org/AL/ . That site should have contact information to organizations that provide low or no cost legal help for qualified persons.
If you are in a position to retain private attorneys, you likely will be able to find many attorneys willing to help.