Will my repentance from zina – which lasted for years – be accepted after I have committed to all the obligatory duties and changed my life? And will the sin I deeply regret be forgiven? And what is my status now?

The one who repents from a sin is like one who has no sin, if the repentance is sincere. You must cut off the relationship with the girl and block all paths leading to sin, and adhere to the five daily prayers. You must also adopt the means of righteousness, such as constant remembrance of Allah (dhikr), supplication (du'a), keeping company with the righteous, contemplating the Hereafter, and being mindful of Allah's constant watch over you.