All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
You have to conceal your sin, seek Allah’s Forgiveness, repent sincerely to Him, and indulge in doing good deeds as much as you can. Thus, Allah will not only forgive your sins, but also He will convert your sins to good deeds according to some scholars who based their opinion on the verse in which Allah Says (what means): {And those who do not invoke with Allah another deity or kill the soul which Allah has forbidden [to be killed], except by right, and do not commit unlawful sexual intercourse. And whoever should do that will meet a penalty. Multiplied for him is the punishment on the Day of Resurrection, and he will abide therein humiliated - Except for those who repent, believe and do righteous work. For them Allah will replace their evil deeds with good. And ever is Allah Forgiving and Merciful.} [Quran 25:68-70]
The Prophet said: "Whoever happens to commit any of these filthy things, should conceal himself/herself as Allah did not expose him." [Al-Haakim]
Therefore, you should not be despaired of Allah's Mercy.
Allah Says (what means): {Say, "O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful."} [Quran 39:53]
Finally, you should avoid mixing with bad people and keep away from being in bad places or bad company. Also try your best to befriend pious persons who will help you in good and protect you with the Help of Allah, from evil.
Allah knows best.