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, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
If the acceptance to which you have referred to in the question means the conclusion of the marriage contract that meets all the required conditions, and that the only thing that is delayed is the wedding, then this girl is your wife as of this date and divorce is the only lawful means to be separated from her.
If you divorce her, she will be entitled to half the dowry specified in the marriage contract.
However, if you mean that you have merely betrothed her, but your circumstances do not help you obtain the necessary resources to marry her, then you can break the betrothal.
Nevertheless, it is better for you to keep your promise as long as your fiancée faces no harm by waiting until you are able to marry her.
Allaah Knows best.