What is the ruling on saying: "By divorce, you will be unlawful to me if you enter this website again," if the wife enters the website again out of forgetfulness?

The wording you used with your wife carries many possibilities, such as حرمة (prohibition), divorce, Dhihar (a form of divorce-like pronouncement), or other interpretations. It's possible the intention was to prevent your wife from accessing the website. Therefore, it is necessary to clarify what was written and what was intended by it to scholars, so they can provide an answer.