What is your advice to me and what must I do to avoid falling into disobedience to my Lord, knowing that I have met a committed girl online three years ago, we have exchanged feelings of love, and I intend to marry her after getting a job?

The way you communicated with the girl, from messaging to phone calls then meeting, is all forbidden and could lead to a moral disaster, because Satan drags a person to sins step by step. You must cut off your relationship with this girl as repentance to Allah, for repentance means abandoning the sin, regretting it, and resolving not to return to it. If you wish to marry her, then let that be by directly approaching her family through the proper channels.