my friend is in huge problem which she doesnt realize

Assalamualaikum
Mufti saab my friend is in huge problem which she doesnt realize.she is engaged to her aunt's son (mother's sister) who is a very nice person but she is in affair with someone else since last nine years,and since last nine years her lover has done nothing but made her cry by goin out in night clubs,smoking and hving affairs with other girls to make her jealous.my friend says that her lover has given up all these bad habits for her but i personally still dont think that he is a nice person.i hv told her many time that her life is not created to be ruined like this with having haraam relationship and that she would be more happy with the person she is engaged to and many other things from the view point of islam.but nothing seems to change her mind,she tells me not to make her understand coz she wont.mufti saab she has tried earlier to stay away from her lover as she knows that its wrong in islam but then her lover calls her up alot n talks to her emotionally which makes her lean back to him.she is an innocent girl who deosnt know how to stick up to her own decisions n can be easily diverted emotionally. she says that even the thought of being away from him brings tears to her eyes.her problem why she cannot stay away from him is that the guy lives right next door to her so she sees him even if she doesnt want to n  hears his voice even if she doesnt want to listen. her two of older cousins know abt the situation n they also tried to explain her alot but she didnt undrestand n so now they dont say anything n left her with her life.but mufti saab i cannot let my friends life get ruined like this n cannot tell about this problem to anyone in her family,thats why i have come to u for your advise.plzzzzzzzz mufti saab tell me something to tell her that would effect her deeply n she understands n stays away from the person.
  plz reply as soon as u can as i need to inform her soon.

jazakallah for your time to awnser .