She is right. Your response is wrong.
Consequence of mortal sin is hell but as been said earlier, with repentance and prayers, no matter how late in our life before death, it can be mitigated, meaning it would not be a mortal sin anymore. How? We leave it to the mercy of God.
So we do not know that 99.9% of the world population is in hell. You are making a judgment by saying that, which the Church does not, not even for one single person the Church would say that he/she is in hell, simply because because we do not judge whether the person dies in mortal sin or not.
Only on principle - that if one dies in mortal sin, then the consequence is hell. The Christian terminology for that is eternal damnation or eternal death or sometimes just shortened to death, like the consequence of sin is death.
As Christians, though many times in our lives we may commit mortal sins, by the redeeming power of Jesus, when we repent or regret of what we have done, God’s mercy and forgiveness is upon us. Thus it leads Paul to say, “Death, where is your sting?”