Am I obligated to release my checking account information in a divorce case due to mandatory disclosure rule?

Depends on the information being sought. Name of bank, account numbers, most recent bank statement-Yes.

Representing yourself in a divorce case, especially in another State, is like bringing a slingshot to a gunfight. He should engage an attorney licensed to practice in that other State right away. Getting a joint checking account before his legal matters were in order was not a great idea. If the laws in the other State are similar to Florida's, then he will likely have to produce the account records, though he may be able to redact information that pertains directly and only to you. He should consult with an attorney in that jurisdiction to discuss the specifics of his situation and his options.

You will have to ask an attorney in the other state.

He has to produce all accounts that are in his name or in his name with someone else, like you. So, yes, he has to produce them or he could face sanctions, including contempt of court, money fines, etc.

He has to produce those documents if his name is on the account. Use of a lawyer is recommended.