Even if we have made mistakes in the past which offended God, we can trust that if we sincerely repent, God will not remain angry at us forever. (Ps. 86:5)
Jehovah disciplined his people in ancient times to the point that it was fair and just, and he will do the same to us today if we fall into sinful practices. (2 Tim. 3:16)
So we should never fear that we are inevitably separated from God.
If he has forgiven us, we in turn have to forgive ourselves.