There is a monumental difference between sin and adversity. Sometimes, these two different scenarios may come at the same time, but they are not the same. In Bruce C. Hafen's Ensign article titled "Beauty for Ashes: The Atonement of Jesus Christ", he discusses a continuum ranging from sin to adversity. One end, sin, being the highest degree to which we are at fault. And at the other, adversity, we may bear no responsibility at all. We are solely responsible for our choices in this life, wrong or right. When we sin, it is because we chose to. We disobeyed one of God's commandments and now face consequences for that sin, whether temporal or spiritual. It is our opportunity and duty to use the Atonement of Jesus Christ and be forgiven for our sin completely. This includes having a change of heart and forsaking the sin.
When things happen to us because of other people's choices, this is known as adversity. Adversity is primarily given to us from a loving Heavenly Father. This may sound odd, but he loves us so much that he wants us to keep getting better and improving. And we all know that to do so, we must be pushed. He will NOT push us beyond our limits, he has promised us this in the scriptures. But we must be tried and tested to prove worthy to live in the kingdom of God. Adversity may leave a bitter taste in our mouth, just as sin, but it is important that we learn the difference between the two so we don't beat ourselves up. Give yourself credit. If you are trying to live the Gospel of Jesus Christ to your best ability, that is ALL you can do. You will be blessed for your diligence and your faith.