Many of us have committed sexual sins. When we repented of these sins, Jesus forgave us and washed us clean. Though we have been truly cleansed and forgiven, guilt can cling to us (Heb 12:1) and cause us to feel that our body is "dirty."
Jesus came to save sinners, not condemn them (Jn 3:17; Rm 8:1). He took on a human body (Heb 10:5). Because of this, our own bodies have a new dignity. The truth is that "the Lord is for the body" (1 Cor 6:13). The Lord looks at your body, which He created, and declares that it is "very good" (Gn 1:31).
Jesus is so concerned for your body that at every Mass, He tells you: "This is My body to be given for you" (Lk 22:19). He gave up His body to purify you "in the bath of water by the power of the word" (Eph 5:26). Our bodies died to sin in this baptismal bath and then rose from the waters of baptism to live a new, holy life (Rm 6:3-4). Now you no longer own your body. It belongs to Jesus, Who has bought you for His own (1 Cor 6:19-20).
Right now, renew your Baptismal promises. Reject Satan, the glamor of sin, and all Satan's empty promises, especially his lies in promising fulfillment and happiness through a lifestyle of sexual sin. Renew and profess your faith in the Father, Son, and Holy Spirit, "Who is within" your body (1 Cor 6:19), and Who fights constantly against your sexual temptations (Gal 5:17).
"Those who belong to Christ Jesus have crucified their flesh with its passions and desires" (Gal 5:24). "My point is that you should live in accord with the Spirit and you will not yield to the cravings of the flesh" (Gal 5:16).