get rid of the curse

Assalamu aleykum! I wanted to ask something. My grandfather's grandfather on my mother's side fell in love with a married woman and ran away with her to another city. The woman's husband cursed them. If the curse touches the descendants of that person, will it affect us? If there is an effect, what should we do to get rid of it? If there is no effect, what should we do for Allah to forgive this sin?