What is the ruling on the divorce of a woman who forced her husband to divorce her and threatened him with a knife, and then he uttered the divorce twice more during the waiting period?

If a husband divorces his wife under duress, threatened by her with suicide, and he believes her threat to be genuine, then his divorce is not effective. However, since he divorced her twice, and had previously divorced her once during a previous pregnancy, she has become irrevocably divorced from him (bainunah kubra). She is not lawful for him again unless she marries another man and he consummates the marriage with her, then divorces her or dies, and her waiting period (iddah) expires. Some scholars are of the opinion that successive divorces before a new marriage contract or reconciliation are counted as a single divorce.