All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.
If what you mean is that a man says to his wife, “If you had done such and such (meaning an action in the past), I would have left you,” then this formula is not suitable for initiating a divorce; rather, it is informing about what could happen. So, if the wife had done that action, then divorce does not take place just because the husband made that statement.
If what you mean is otherwise, then please clarify that to us so that we could answer accordingly.
It should be noted that (left you) is not an explicit term of divorce. For more benefit, please 89074.
Allaah knows best.