Is contact (of a jinn) the cause of the problems the questioner faces in his life, and of his relationship with the girl he wishes to marry despite his family's opposition and his doubts about her sincerity?

If you see the girl as having good character and religion, and that what was mentioned about her is a fabrication or that she has repented, then it is permissible for you to marry her. We advise you to ask your mother to verify her situation. If she sees good in her, then let her propose to her on your behalf. Otherwise, do not prioritize the satisfaction of a girl over the satisfaction of your parents, unless you fear falling into the forbidden due to your strong attachment to her. In that case, marrying her takes precedence over obeying your parents by leaving her.

Before marriage, you must keep away from her because she is a non-mahram, and it is not permissible to be alone with her, touch her, or speak to her without a valid need. You must also repent to Allah Almighty for what you mentioned about fornication, because it is not permissible for a fornicator to marry a chaste woman until he repents.