What is the ruling on the marriage of the questioner, which took place under duress from her mother, and what is the fate of her mother for doing that, and is it permissible for her to ask for forgiveness from her former fiancé after all these years?

It is not permissible to compel a girl to marry someone she does not desire. A marriage under duress is not valid unless the girl later approves of it and consents to it, as happened with the girl who came to the Prophet, peace and blessings be upon him. If the woman does not approve of this marriage, then it is invalid.

The mother may be excused for what she did in forcing her daughter to marry, thinking that she was doing what would bring happiness to her daughter, though she was mistaken in that.

There is no sin upon the girl for not marrying the first suitor, as breaking off an engagement is permissible without cause. There is no liability on her if the suitor falls ill or is distressed, or if he thinks she betrayed him. Breaking off an engagement is not considered betrayal, and it is permissible.

The girl must forget this matter and not think about apologizing to him or contacting him, as this is from the whispers of Satan. The advice is for her to occupy herself with what benefits her, and to take care of her husband and children, and not to grieve over what she missed, for it might have been an evil that Allah averted from her.