First of all, mom's "handwritten, notorized custody paper" does not give you custody. Only a court order does that. It certainly does not make you his "mom" now. In order for you to become his mom, you have to adopt him. Right now, you are merely a caretaker -- not even a legal guardian, since there is no court order granting you guardianship. You need to file to adopt him. At the time you adopt him, the court will change his last name to yours and he will legally be your son. If you don't want to actually adopt him, then at the very least, you need to file for legal guardianship over him. You don't mention his father, other than to say he is dead, but if there are other relatives out there (grandparents, for example), they could have a legitimate claim and if you don't get guardianship, or adopt him, you could find yourself served with papers that remove the child from your household.
Please talk to a good family-law lawyer in your area right away, and get this taken care of before you have a mess on your hands. If you click on "find a lawyer" at the bottom of this Avvo site, then put in "family law" and "Paragould, AR", you will be able to find a good one.
No attorney-client relationship is established with this answer. It is not to be considered legal advice, but is merely given to point you in the right direction and give you a general answer as to the law regarding the question you have asked.
Ms. Reece's answer is spot on. Many people are under the impression that because a parent writes out something on a piece of paper and has it notarized, that the notary makes the writing a legally binding document -- but it does not. The jurat of the notary simply means that the notary has verified that the document was actually signed by that person.
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