Because your husband was still married to someone else at the time, your marriage is null and void. Many people like to get an annulment, so that the paperwork in the vital records office is straight and for other reasons, such as making changes to health care coverage, but it is not required. Also, when there are property issues involved, an annulment may be necessary to straighten out what belongs to whom.
This answer is given in accordance with the laws of Virginia and may not be applicable in any other state. It should not be construed as legal advice, as that would require a more thorough analysis of all of the facts involved in a specific case.