What is your advice, may Allah preserve you, for one who has fell into the sea of desires and doubts?
My advice, for him is to repent to Allah and that he recalls the statement of Allah the Blessed and Most High,
Say: “O ‘Ibâdî (My slaves) who have transgressed against themselves (by committing evil deeds and sins)! Despair not of the Mercy of Allâh, verily Allâh forgives all sins. Truly, He is Oft-Forgiving, Most Merciful (Az-Zumar: 53)
Therefore, even if you were swimming in a sea of disbelief, you have indeed performed good, by way of repenting to Allah the Blessed and Most High, because the door of repentance is open for all of the servants. So, upon him is to repent to Allah and return to the truth.
Source an audio with title: Asbaab al-Inhiraaf wa Tawjeehaat Manhajiyyah: from Shaykh Rabee’s (hafidahullah) official website.