Is the wife considered to be irrevocably divorced by three pronouncements based on the events mentioned: her husband swearing to divorce her if she was the one who wrote a certain topic (which she denied), his saying to his mother, "Your daughter will not remain married to me after today" (and she was menstruating), and his saying, "You will be divorced by three pronouncements if you have a relationship with any of your colleagues" (and she had messaged a colleague to apologize, not to communicate, and entered a chat once and quickly left)?

Divorce during menstruation is valid despite its prohibition, and a contingent divorce takes effect upon the occurrence of the condition it is contingent upon. Therefore, your first divorce is valid. The husband's statement: "You will not be under my responsibility after today" could be a promise or an immediate pronouncement. If he intended an immediate pronouncement and intended divorce with this wording, then it is a second valid divorce. As for the third instance, which is contingent upon the existence of a relationship between you and young men, its validity depends on the husband's intention in defining the type of relationship and its timing (present or past). If you had relationships with young men as intended by the husband, then the third divorce has occurred. These matters should be presented to the Sharia court or trusted scholars.