In the US, the ways for a marriage to be terminated is by death or by a decree of a competent court.
So, if your husband is still living and neither of you have obtained a divorce decree from a court, you two are still legally married with each other.
Are you still in contact with the husband? Perhaps he has obtained a divorce decree.
If you cannot find your husband and cannot confirm the status of your marriage, you can check with an attorney in the state where you are living to find out its procedures on divorce. In many states, such as WA, the status of the marriage can be terminated by a court even if the other spouse cannot be found. Proper procedures would need to be followed.
In Maryland there is no such automatic divorce. But, you do have grounds to get a divorce. If there are no children and no property issues involved, you may be able to do it on your own. Otherwise, you should at least consult with a lawyer.