Chinaza,
You must understand that those thoughts are not coming from you, they are coming from outside forces--dark forces that rejoiced every time you obeyed their promptings that resulted in a life of sin. Now that you are in Christ Jesus, you have become a "New Creature," that is why what you so freely did before, bothers you so much now. Your nature has been changed from sin to holiness. Your struggle is an internal struggle that the forces of darkness are taking advantage of because you do not yet know that your battle is not with flesh and blood. It is written that God Himself "rescued you from the dominion of darkness and transferred you into the Kingdom of His Dear Son Jesus, in whom you have full redemption." Col. 1:13-14.
You must learn to walk "in the spirit" and ignore the appetites of "the flesh." To understand this, you must recognize that the spirit that Paul is talking about here is not the Holy Spirit, but he is actually referring to "your Regenerated Spirit." You have been brought from death to Life by way of your acceptance of Jesus and believing in His name. God grafted you into His family and you do not belong to the world nor does the prince of the power of the air have any legal rights to be in your life.
According to 2 Cor. 5:17--"You are a New Creation," but you will have to learn to walk that way. I would suggest spending time with The Father in the morning, Jesus in the afternoon and then at least 1/2 hour with the Holy Spirit at night before you go to bed. Make the effort to "renew your mind," so that you are thinking God's thoughts and not the thoughts of the old man. Also, when you came to Christ, you were also "deputized" and have been given "authority," and the legal right to the use of the name of Jesus. We are instructed to "cast down vain imaginations and everything proud and lofty thing that tries to set itself against the knowledge of God." We are to make those things bow to the obedience of Jesus Christ... not our own. Please make your Bible a vital part of your day. So many people live in defeat when God spared no expense to have us walk in Christ's victory--all because we are of the Truth that will set us free in every way... please take advantage of the keys to the Kingdom that you have been given.
Hope this helps,
Regenerated 1