I wanted help for my friend. She went through family problems when she was 13 years old and she was away from them and their care, that caused her to get into a haram relationship that made her feel that she has a company and after 6 years they want to make it halal by doing nikah. But 3 years back he cheated on her she went almost went through a trauma as her loss of family members got her very attached to him and she was in severe depression for 3 months. Everytime she stops talking to him she gets nightmares which cause her to wake up in the middle of the night and cry she prays a lot and feels guilty for her sin and she repents. Now shes 18 and he is 18 too and they want to marry but he keeps hurting her and I advise her to move on but doesn't help. What can be done in this situation?

1- If he keeps hurting her, you must encourage her to move on. Assure her she will be ok. It takes time but she will be ok.

2- Ask her to read these Duas before she sleeps to stop those nightmares:

Do Wudhu right before you sleep

Be on your right side when you are falling asleep

Read Sura Falaq and Naas before falling asleep

Read this Dua before sleeping:

آمَنْتُ بِاللَّهِ وَ كَفَرْتُ بِالطَّاغُوتِ، اللَّهُمَّ احْفَظْنِي فِي مَنَامِي وَ فِي يَقَظَتِي

Read this Dua as well:

أعوذ بما عاذت به ملائكةُ الله المقربون وأنبياءُ الله المرسلون وعبادُ الله الصالحون من شر رؤياي التي رأيت أن تضرني في ديني ودنياي

Then she blows to her left side 3 times.

3- Ask her to read thos Du’a daily to help her with her situation:

https://www.duas.org/Amn.htm