One morning while getting ready for church, I braced myself knowing that I would indubitably run into those who have tried to hurt my family by word and deed. I was comforted by the thought that Mass is a microcosm of the Last Judgment: everyone will be there, good and evil, whether we like it or not...there is just no way to avoid it, since presence will be required. Remembering the eschatological dimension of Mass will get one through anything. A friend reminded me of the words of St. Thomas Aquinas from Lauda Sion: Sumunt boni, sumunt mali: sorte tamen inaequali, vitae vel interitus. ("Both the wicked and the good eat of this celestial Food: but with ends how opposite!")
In the meantime, it is a bit like going to Mass with the Borgias. They might be a bunch of sociopathic wretches but then they have to save their souls, too. After all, the Church is a hospital for sinners, myself included. We each must answer to God for our own behavior, not the behavior of others. Praying for our adversaries can seem to require superhuman effort at times but then it also opens the door to peace, forgiveness and, ultimately, to Heaven.