Are the phrases used in a state of extreme anger, such as "You are no longer of any use to me" and "I don't want you anymore," considered a divorce, especially with their repetition and entering into seclusion after uttering them, and does the wife become unlawful to the husband as a result?

Your statement to your wife: "You are of no use to me anymore" and "I don't want you anymore" are allusive divorce phrases (kinayat al-talaq) by which divorce does not occur unless intended. If you intended divorce with these words, a revocable divorce (talaq raj'i) takes place. If you did not intend it, or doubted the intention, it does not take place. As for divorce during extreme anger, where a person loses control of himself, it does not occur, even if you intended it. It is advised to fear Allah, handle matters with wisdom, and avoid divorce pronouncements.