Wedding Slashers(2006)

Jenna is a young woman that has lost every man she loved since she was very young. Now she has encountered Alex and they decide to move in together and get married. She has told him that she lost her parents but in the church, she glances at her parents and she decides to call off the wedding. She asks to her friends to leave the church and she discloses the story of her family to Alex. Meanwhile all their friends are murdered by killers and Jenna tells that they are members of her family. Why are they killing her friends?