Sin breaks fellowship. It does not change relationship.
We must recognize and acknowledge our PRESENT sins, confess and repent, and be forgiven. The verses below apply to believers -- to Christians who have been saved by grace but are nowhere near sinless perfection (since none are).
8 If we say that we have no sin, we deceive ourselves, and the truth is not in us.
9 If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
10 If we say that we have not sinned, we make him a liar, and his word is not in us.
At the same time, none of us believers is under the power of our sin nature. "Sin SHALL NOT have dominion over you". So our focus must be on righteousness and holiness.