It may help you to think of the Holy Martyrs. They had free will till the end, and chose to suffered persecution and death for their love of Jesus Christ.
Your free will does not end until your mental faculties are diminished through loss of consciousness, or some mental disorder, or through physical manipulation (someone ties you down so you can’t get to Mass).
Just because you’re body is threatened, does not mean your will is threatened, but you’re culpability may be lessened.
From the Catechism:
1754 The circumstances, including the consequences, are secondary elements of a moral act. They contribute to increasing or diminishing the moral goodness or evil of human acts (for example, the amount of a theft). They can also diminish or increase the agent’s responsibility (such as acting out of a fear of death). Circumstances of themselves cannot change the moral quality of acts themselves; they can make neither good nor right an action that is in itself evil.
1808 Fortitude is the moral virtue that ensures firmness in difficulties and constancy in the pursuit of the good. It strengthens the resolve to resist temptations and to overcome obstacles in the moral life. The virtue of fortitude enables one to conquer fear, even fear of death, and to face trials and persecutions. It disposes one even to renounce and sacrifice his life in defense of a just cause. “The Lord is my strength and my song.” “In the world you have tribulation; but be of good cheer, I have overcome the world.”