Does a divorce take effect with the words "You are divorced, divorced, divorced, and forbidden to me like my mother" to a pregnant wife, knowing that the marital life continued for 16 years thereafter?

The ruling on repeating the word of divorce has been previously explained. If the intention behind each utterance was to initiate a new divorce, then three divorces have occurred, and the wife becomes irrevocably divorced (baynunah kubra). In this case, the relationship must be severed immediately, and one must repent to Allah. If the intention was not to repeat the divorce, then only one divorce has occurred. As for your statement, "You are unlawful to me as my mother is unlawful to me," this constitutes zihar, and it entails the prohibition of sexual intimacy before expiation is performed. One must repent for any intimacy that occurred before the expiation.