In Maryland, a spouse may invoke marital privilege to avoid testifying against their husband/wife. Rather than waiting to be called as a witness before informing the State's Attorney you do not intend to testify against your husband, I suggest you call them in advance. Since your testimony is likely their only substantive evidence against your husband, the charges will most likely be dropped.
However, two things are worth remembering: (1) giving false statements to law enforcement is a crime; or (if the statements you gave were true) (2) nobody should tolerate being the victim of physical or emotional abuse.
Please consider your actions carefully. Domestic abuse is a serious issue, and grounds for immediate divorce in the State of Maryland.
The State's Attorney in Maryland decides whether to prosecute. It's not your decision at this point. My colleague is correct in that you may invoke a spousal privilege, however you can only do this one time. So if you've used it before, this route won't work. You should consider your choice carefully on how to proceed. Domestic abuse is serious and prosecutors take it that way.
This is not legal advice nor does it create an attorney-client relationship. This is for education and informational purposes only. It is always recommended that you contact an attorney with any concerns as each individual case is unique.