All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
First of all, you should know that Islam does not approve of any affectionate relationship between a man and a woman before marriage as we clarified in Fatwa 81356. If the case is that you committed fornication with him, then this is a great calamity, because Zina (fornication or adultery) is one of the grave major sins and abominable acts that incur the Wrath of Allaah.
Therefore, you should endeavor to repent to Allaah from committing fornication and from abandoning the prayer. However, to achieve repentance, you have to give up the sin, regret having done it, and be determined not to do it again, while concealing your sin and performing as much as you can of good deeds so that your sins will be wiped out; for more benefit, please refer to Fatwa 86527.
Moreover, you should know that it is not valid to marry that man on this condition, but if he sincerely repents and the signs of being steadfast upon Allaah’s religion become apparent in him, and you repented as well from committing fornication, then you may agree to marry him. For more benefit, please refer to Fataawa 81160 and 89531.
With regard to how a husband should treat his wife in Islam and the ruling on him beating her, refer to the following Fataawa: 86618, 84120 and 85402.
Allaah Knows best.