So, as Fr. Hardon makes clear, this is not a frenzied act of feeling but the will to love God primarily for His goodness, and not from fear or lesser motives, though they may coexist with the predominant motive. There is no way of knowing with an absolute certainty if one has made a perfect act of contrition, but all that is required is the standard of all human action, moral certainty. If you can say an act of contrition in these or similar words truthfully, intending it, then I think you would have moral certainty.
O my God, I am heartily sorry for having offended Thee,
and I detest all my sins, because I dread the loss of heaven, and the pains of hell;
but most of all because they offend Thee, my God, Who are all good and deserving of all my love.
I firmly resolve, with the help of Thy grace to confess my sins, to do penance and to amend my life. Amen.
