Is constantly thinking about an old sin, causing severe panic, and abandoning Friday prayer out of fear of the matter being exposed, considered a psychological illness? And how can one overcome intense fear upon hearing verses and hadiths of intimidation?

Whoever falls into sin should hasten to repent and seek forgiveness. Sincere repentance involves abstaining from the sin, regretting it, and resolving not to return to it. Allah accepts the repentance of those who repent and rejoices in it.

As for abandoning Friday prayer under the pretext of avoiding hearing what might result from the sin, this is impermissible. Friday prayer is an obligation, and a severe warning is incurred for abandoning it without a legitimate excuse. This is a ploy of Satan to deprive the Muslim of performing the obligation.

There is no harm in consulting a trustworthy psychiatrist.