The AA Big Book gives a great strategy for dealing with and overcoming resentment. Pray a resentment prayer for someone you resent for two weeks (even if you don't feel like it or want to) and see what affect it has on you. Ask for everything you want in your life for the person/s you resent. Below is a prayer I came across, author unknown, that I have used when I identify resentments I want to address.
Father, I ask You to bless (insert name of person for whom you are holding resentment). Show them a new revelation of Your love and power. Holy Spirit, I ask You to minister to their spirit at this very moment. Where there is pain, give them Your peace and mercy. Where there is self-doubt, release a renewed confidence through Your grace. Bless their homes, families, finances, their goings and their comings. In Jesus' precious name, Amen.