Hello dear Elyzabet,
What is happening to us when we stumble as born again Christians is the nature of our flesh. We are sinners. But, when we accept Jesus we accept the Holy Spirit into our lives as well. The Holy Spirit will convict us of our sins. Conviction is NOT condemnation. The Holy Spirit wants us to recognize our weakness for sin and repent (change) our ways completely. Therefore, the journey that you are on is one of repentance and acceptance.
By staying close to God and his word for us the Bible we become stronger and stronger. Even those of us who have been on this journey longer are still convicted by the fact that sin is a struggle. But, the Holy Spirit is our source of guidance and strength. That is why Jesus gave us him.
Stay close to the Lord on your walk with him. Hold his hand and remind yourself of who you are in Christ when those moments happen. Don't beat on yourself. Acknowledge what you have done to God. Seek his help to not continue and the more you practice being who God made you to be the better it will get. Prayer is our best weapon against the weakness we experience.
we will all sin, we still have our fleshy nature to battle. once saved always saved.