Are the spouses considered Islamically divorced based on the events mentioned, and if not, how many divorces have occurred?

Divorce occurs the moment the husband sends a message to that effect; it does not depend on witnesses. If your husband returns you by a message to that effect and you are still within the 'iddah (waiting period), then the return (revocation of divorce) has occurred. The 'iddah varies depending on the woman's condition: if she is pregnant, her 'iddah is until she gives birth; if she menstruates, it is three menstrual cycles; and if she does not menstruate due to young age or menopause, it is three months. So, if the husband definitively states his intention to return and you are still within the 'iddah, then you are still spouses. If he does not state it definitively, or if you have exited the 'iddah, then there is no return. In the event that the return does not occur and the 'iddah ends, and if only one or two divorces have taken place, the spouses can remarry with a guardian, two witnesses, and a dowry. However, if the 'iddah has not ended, he can revoke the divorce.