He is physically and mentally ill from concealing his sin from everyone. He becomes sickly pale, and even resorts to harming himself as a form of punishment. This includes him whippings his back and fasting for periods of time. His deteriorating health can be shown in his cheeks as they are “paler and thinner”(83) and his voice is more “tremulous than before”(83). Mentally, it has affected his work and his ability to perform it well. After eaten away by this sin had become too much, Dimmesdale confessed to the church and the congregation present during his sermon. However, due to his high stature in the community, the church believes he can do no wrong and does not believe his confession. This only makes his guilt worse, as he can't be forgiven for what he has done.
Hester and Dimmesdale both committed the shameful sin of adultery. The difference between the two is that Hester expressed it and Dimmesdale concealed it, he kept it hidden from the public. Hester, making the wise choice and accepting her sin, was able to continue to go on with her life. Dimmesdale however, kept the sin locked up inside and the guilt started to eat away at his