You must obey the subpoena, but if you are called to testify you can tell the court/jury that you have no recollection of the incident or your statement if that is the truth. The state obviously won't listen to you and even if you retract your statement the state can still decide on its own if it wants to proceed with the charges.
If all they have to go on your your words and you won't testify, one would think that the state does not have much to convict your husband with. What other factors does the state have? How is he even facing a trial?
This is not legal advice. If order to give you legal advice i would need to see the Tickets and talk to the court first. Good luck:)
To meet the burden of proof with a battery charge, they need to prove that he exercised contact with you without your consent. However, depending upon what is alleged, the State may be able to meet the elements of a disorderly conduct charge even without your testimony. You need to testify , but you need to be truthful.