Repent to Allah!
No matter how big you think your sin is, remember that Allahs mercy is bigger. We all make mistakes, we sin, and we regret. Allah loves those who regret and ask for forgiveness! So dear brother and sister repent to Allah, Our Lord, the most Merciful and Forgiving! And as you wish Allah to forgive you, you should forgive others! Islam is about forgiveness, caring and humanity, let us remind one another about that as often we can!
"Repentance is the most noble and beloved form of obedience in the eyes of Allah Ta'ala.He loves those who repent and it is because of His love for His creation that He tests them with sins so that He may shower His blessings and favours upon them after they repent" (Imaam Ibn Qayyim rahmatullahi alaihe)