Well, where do I start? I'm 21 years old. I have a child and a girlfriend whom I love so much! But recently, I committed a sin -- I commited adultery! I feel really bad, so bad I cry myself to sleep sometimes. I feel awful! I feel disgusted with myself! I can't sleep or eat or enjoy my life anymore. I need help fast! It's gotten to a point were I just don't want to live any more! I let my child and my fiance down!
I've been trying to change my ways, and I just started going to church. It's been over five years since I been to church. When I arrived at church I didn't know what to do. I want God to come to me and give me peace in my mind and body. I want Him to show me the way. I want Him in my life.
Let's start by getting things in perspective. You've been committing a number of sins in your life. Among them you've been committing fornication with your girlfriend and that resulted in a child being born. While you are planning to marry this girl, you recently had sex with another girl. This isn't adultery because you have yet to be married. What you did was continued your fornication with multiple girls instead of just one. It doesn't make it any better -- it is still a sin -- but it doesn't change the fact that you are drowning in sexual sins.
"Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God. And such were some of you. But you were washed, but you were sanctified, but you were justified in the name of the Lord Jesus and by the Spirit of our God" (I Corinthians 6:9-11).
I don't know enough about what is going on in your life, but it appears you are trying to change by going part-way instead of fully into being a Christian. As Jesus pointed out, "No one can serve two masters; for either he will hate the one and love the other, or else he will be loyal to the one and despise the other. You cannot serve God and mammon" (Matthew 6:24). You want God in your life, which is great! But that means you need to go to God because you are the one who left Him. "Adulterers and adulteresses! Do you not know that friendship with the world is enmity with God? Whoever therefore wants to be a friend of the world makes himself an enemy of God. Or do you think that the Scripture says in vain, "The Spirit who dwells in us yearns jealously"? But He gives more grace. Therefore He says: "God resists the proud, But gives grace to the humble." Therefore submit to God. Resist the devil and he will flee from you. Draw near to God and He will draw near to you. Cleanse your hands, you sinners; and purify your hearts, you double-minded. Lament and mourn and weep! Let your laughter be turned to mourning and your joy to gloom. Humble yourselves in the sight of the Lord, and He will lift you up" (James 4:4-10). That means you have to stop doing things your way and start doing things God's way.
Being a Christian is far more than just going to church services. It is a dedication to a way of life that is radically different from what the world accepts. So first off, you need to be determined to stop sinning. You may not always be successful, but you have to apply yourself to improving. The second thing is that we need to discuss whether you have fully and truly become a Christian or are only calling yourself a Christian. For that see: