ANSWER:

You must stop all communication and contact with her immediately and sincerely repent to Allah while showing deep remorse for this Haram relationship and after that you can approach her father and proceed with the marriage if you think that she would be a good Muslim wife and a good mother for your children. But if you think that your children would grow up to be like you and her, you are better off marrying a real practicing chaste Muslim woman. 

QUESTION: I am 21 years old man studying in university. I fell in love with a girl and started a relationship. It’s been 6 months. I’m ready to marry her as her family accepts me. But since I have done haram relationship with her, should I breakup and repent or should I continue my approach of marrying her?