First, congratulations on being engaged and may Allah (SWT) facilitate for you this marriage if it is good for your faith. You are truly blessed to have parents who are working in the path of Allah and who are open hearted enough to consider helping the family of your fiancé by marrying you to their daughter. We urge you to make lots of du’aa (supplications) to Allah, and to continue to seek His guidance and assistance through the Istikhara prayer for guidance as you finalize the discussions on the marriage.

Second, we can understand how painful it must have been for you to hear from your fiancé that she was sexually abused. We are taught in society to focus much attention on sexuality and chastity and therefore you might be concerned about the virginity and chastity of your fiancé. You have a right to feel saddened, but all is not lost by the grace and mercy of Allah. Instead of looking at this situation in a negative light, think of the many positive aspects: your fiancé felt that she should be honest with you before you marry her, and tell you about her experience as a child; by Allah’s will, your fiancé did not reach puberty until she was 14 years old – this does not negate the devastation she might have felt as a victim of sexual abuse, but it is important in the sense that she might not have been mature sexually. You can at least be grateful to Allah that her chastity was not violated after she had reached an age when she could experience sexual stimulation or even satisfaction. She is innocent of that which was done to her; she is a victim after all. It was Allah’s will that your fiancé shared with you this experience from her childhood before the marriage. Now the decision will be yours whether you are able to marry her with a clear mind and clean heart by contextualizing her experience as being something which occurred during her childhood, against her wishes, and which violated her rights as a child but because of the age at which it happened, in her case, did not cause her to lose her virginity or even experience sexual satisfaction.

Third, as you plan for this marriage, be grateful to Allah and seek protection from Allah so that you do not become arrogant and consider yourself as doing your fiancé and her family some sort of favor by marrying her despite their financial situation, and despite her childhood experience. All of the wealth we have is by the blessing of Allah, His generosity, and His benevolence. Therefore, it could be that she is better than you, and could be the source of motivation which causes you to be more conscious of Allah and ultimately to reach Paradise. Do your best to process your feelings about her sexual abuse now, before marriage and promise yourself that you will never again bring up this abuse to her after marriage. Let her know that you appreciate what she has told you, and that you want her to get counseling if she feels she needs to process her feelings about the abuse. Verify with her that she has gotten over that experience, that she does not remember really what happened, and that she was only letting you know as a matter of full disclosure. If that is the case, thank her, show her your appreciation, and give her heart assurance that you will marry her for who she is today and with the mutual promise that both of you will be supporters one of another in your goal to please Allah and to be worthy of Paradise.

Finally, do not tell anyone else about what your fiancé has told you as shaytan will do his best to ruin the prospects of you marrying a righteous young woman. Make the Istikhara prayer and turn to Allah for guidance and assistance so that you can make a final decision about whether or not to marry this young woman. If you can truly put aside your feelings of pain and trust in Allah to grant you a righteous wife, Allah will insha-Allah make smooth for you the path to marriage. Make lots of du’aa and be thankful to Allah for all of the blessings He has granted you.

And Allah knows best. 

For your further guidance, please try the following link(s):
Wife's Emotional Rights
Protect the Innocent, Myself, and My Marriage