Is obeying one's mother and refusing to marry a divorced woman because of the mother's refusal considered an injustice to the woman, especially after she invoked a curse upon the young man and his family?

Familiarity between genders and love relationships are not sanctioned by Sharia. The general principle is that it is commendable to marry a virgin, but marrying a non-virgin is permissible and may even be preferable in some cases. If you see a benefit in marrying a non-virgin, strive to convince your mother. If she does not agree, then obey her, unless refraining from this marriage would cause you harm. The woman has no right to supplicate against you or your mother for not marrying her.