All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Marriage is one of the great matters that need a lot of deliberation so that the Muslim takes the reasons that would help him in completing the marriage in a good manner. Hence, he makes a good choice and undertakes other matters which prevent the annulment of the engagement or the occurrence of divorce, especially if the husband issues divorce before the completion of the wedding and before consummating the marriage with the wife. If this happens, then it causes a lot of embarrassment to the other party. It seems that this is what happened with what you did with this girl and her family, and this is what you should have taken into account beforehand.
In any case, there is no sin on you for what you did, and you are not unjust to this girl or her family. If you invalidated the engagement then that is permissible, but it is disliked without a need. The same thing applies to the fact if you had divorced her before the consummation of the marriage; divorce is permissible but disliked without a need. So, you are not unjust to the girl or to her family. Therefore, her mother has no right to curse you; we hope that her supplication will not be answered because it is an unjust supplication.
If this girl is of religious and moral character, and you can convince them to agree to complete the marriage, then it is a good thing.
Nonetheless, we draw your attention to perform Istikhaarah beforehand because it is one of the greatest reasons for being enabled to success and goodness, Allah willing.
Allah knows best.