I need this page from the Scarlet Letter explained?

"Yea, woman, thou sayest truly!" cried old Roger Chillingworth, letting the lurid fire of his heart blaze out before her eyes. "Better had he died at once! Never did mortal suffer what this man has suffered. And all, all, in the sight of his worst enemy! He has been conscious of me. He has felt an influence dwelling always upon him like a curse.