What is the ruling on retracting an oath of "By divorce, you will not open Facebook again," and what is the expiation for that?

Swearing by divorce (talaq) falls under the ruling of conditional divorce, meaning it cannot be revoked. Therefore, if the wife opens her Facebook page, the divorce occurs according to the majority of jurists, and this is the relied-upon opinion for us. The husband should be cautious and not be negligent in matters of swearing by divorce.