Hello!
I'm going to be very vulnerable here. I have been a Christian for 10 years. I was engaged with someone I was so in love with and then in 2019 found out he was cheating on me. God held my hand throughout the whole situation, I have never felt more happy and more blessed! However, recently, someone from my past came back into my life after 10 years, he was my first love (I wasn't a Christian at that time) and I just knew us talking was trouble!!! But the temptation was sooooo strong

not only did we end up sleeping together while he was engaged, it continued after he got married as well .... I never even had sex with my ex fiance so I have no idea how I let all this happen..
Really? If this is truly what you think, I wonder if you've actually repented of this sin. Repentance requires that you change your thinking about your sin, understanding and rejecting the lies and thought-dynamics that brought you into the sin. If you don't understand these things and how they brought you into sin, though, how will you recognize and reject them if/when they arise within you again? Repentance isn't merely acknowledging your sin and feeling badly about it but changing your
thinking about your sin, adopting God's truth in its place and centering yourself in it and under it.
Crocodile Tears.
At the heart of all sin is Self, the "old (wo)man" the apostle Paul called him (or her). It's who we are without God, when we have a heart ruled by our will and way, when we sit upon the throne of our hearts rather than our holy Maker. Have you dealt with Self in the way the Bible prescribes? If not, "sin crouches at the door," ready to spring upon you, moving you again into behavior you will, in the midst of shame and guilt, wonder at in confusion.
I finally stopped it and repented and confessed everything to my pastors and have been so open about it because I refused to allow that sin to grow! The moment I confessed it I felt soooo free!
Even the lost sinner feels relief (what you call "free") when they admit to doing wrong. This feeling of relief is merely their conscience acting as God intended it to, pricking them terribly when they violate it and quieting when it is acknowledged and followed. But relief from the pangs of conscience through confession of wrongdoing is not necessarily indicative of things being properly restored between you and God any more than it would be for the guilty atheist who finds relief from his conscience by admitting to having done something morally wrong.
When God is in your repentance and confession of your sin, He will lead you into the truth about why you sinned and the way to freedom from it and all other sin. The cleansing work of God in response to your sin will take you deeper with Him, farther into a life lived under His constant control, and into a life more carefully constrained and order by His truth and an ever-growing love for Him. Is this what has happened?
But I'm still struggling with guilt, how can I face God??? How does he forgive me after literally being the other woman in someone's marriage??? I got cheated on so I know how it feels so now I just feel like I'm sooooo undeserving of a good marriage in the future

my pastors have been so amazing to me and have encouraged me and there have been so many moments where God used other people to speak into my life but still I feel undeserving.
You are always undeserving of God's mercy and grace. We all are. God extends His love and forgiveness to you because He is a loving God and because of what Christ has done for you on the cross, paying for your adulterous sin with his own blood and life. This is so for us all. As the hymnist wrote,
"Nothing in my hands I bring,
Only to thy cross I cling."
We are accepted by God solely because of Jesus (
Ephesians 1:6; John 14:6; 1 Timothy 2:5). None of us in-and-of ourselves can ever earn God's acceptance. We would have to be perfect to do so, which is impossible. And so, we must trust in Christ to be for us what we can't be for ourselves: Our Saviour, our atoning sacrifice, our perfect righteousness, our Redeemer. (
1 Corinthians 1:30)
I already feared marriage before and now I fear it even more because I feel like I'm going to reap what I Sowed.
If this was the way God dealt with us, if God gave us what we deserved, we'd all be in hell. You will repeat your sin, though, if you have not learned the "way of escape" from sin God has provided to His children, and are living in daily submission to God's will and way.
I didn't care if people judged me I have already used this situation to help others but how do I get past this feeling?
By knowing, believing and, by faith, standing upon the truth. If you are God's child, you have forgiveness in Christ. Upon confession of your sin, his blood cleanses you from it (
1 John 1:9). This is the truth no matter what you feel or how strongly you feel it.
Consider the apostle Paul's advice:
Philippians 3:12-14
12 Not that I have already obtained it or have already become perfect, but I press on so that I may lay hold of that for which also I was laid hold of by Christ Jesus.
13 Brethren, I do not regard myself as having laid hold of it yet; but one thing I do: forgetting what lies behind and reaching forward to what lies ahead,
14 I press on toward the goal for the prize of the upward call of God in Christ Jesus.
No one becomes more like Jesus by staring at, and bemoaning, their sin. Forget what is in the past and press on toward the "upward call of God in Christ Jesus." Keep your eyes fixed on Christ and don't look away. (
Hebrews 12:2-3; 2 Corinthians 3:18)