The Collaborative International Dictionary of English v.0.48:

Despiteful \De*spite"ful\, a. [See Despite, and cf.
   Spiteful.]
   Full of despite; expressing malice or contemptuous hate;
   malicious. -- De*spite"ful*ly, adv. -- De*spite"ful*ness,
   n.
   [1913 Webster]

         Haters of God, despiteful, proud, boasters. --Rom. i.
                                                  30.
   [1913 Webster]

         Pray for them which despitefully use you. --Matt. v.
                                                  44.
   [1913 Webster]

         Let us examine him with despitefulness and fortune.
                                                  --Book of
                                                  Wisdom ii. 19.
   [1913 Webster]

WordNet (r) 3.0 (2006):

despitefully
    adv 1: in a maliciously spiteful manner; "pray for them that
           despitefully use us" [syn: despitefully, spitefully]