This is the Husband-Wife Privilege which is codified in Florida Statute 90.504. However, this privilege is not what most people think. The privilege allows either spouse to refuse to disclose or prevent the other from disclosing any communications or statements made to each other. It does not allow you to refuse to testify about the actions your spouse may have made.
If you do not want to prosecute your husband/wife you can go to the State Attorney's Office or your spouse's attorney (if he/she has one) and tell them that you want to file a Declination of Prosecution. This does not mean that the State can not proceed with the case, but sometimes the State will take this into consideration in deciding how they want to proceed.
My colleagues answer above is absolutely correct. The rule is meant to not force one spouse to testify about things the other spouse said to him or her in confidence.
It specifically does not apply in a criminal proceeding in which one spouse is charged with a crime committed at any time against the person or property of the other spouse, or the person or property of a child of either.