Having looked up and read some of these Bible passages, in the main they seem to be supporting what she wants to say, ie:

1) Sex is evil. Colossians 3:5. Matthew 5:28.
Spoiler Alert, click show to read: 
So put to death your worldly impulses: sexual sin, impurity, passion, evil desire, and greed (which is idolatry). Colossians 3:5.
But I say to you, anyone who stares at a woman with lust for her has already committed adultery with her in his heart. Matthew 5:28.


2) We are all sinners. Romans 3:22-24. Matthew 7:13-14.
Spoiler Alert, click show to read: 
even the righteousness of God through faith in Jesus Christ for all those who believe; for there is no distinction; for all have sinned and fall short of the glory of God, being justified as a gift by His grace through the redemption which is in Christ Jesus; Romans 3:22-24.
“Go in through the narrow gate, because the gate is wide and the road is spacious that leads to destruction, and many people are entering by it. How narrow is the gate and how constricted is the road that leads to life, and there aren’t many people who find it!” Matthew 7:13-14.


3) Her way is the only true salvation (unbelievers and heathens like me are doomed...) and this is manifestly obvious.
Spoiler Alert, click show to read: 
that if you confess with your mouth Jesus as Lord, and believe in your heart that God raised Him from the dead, you will be saved; Romans 10:9.
For since the creation of the world His invisible attributes, His eternal power and divine nature, have been clearly seen, being understood through what has been made, so that they are without excuse. Romans 1:20.


In other words she has selcted particular sections with the aim of convincing you that she is right. Which is fine.

Now to counteract that find some verses that support her ex's/your side/ a different viewpoint to hers. Then you can get some discussion going.

Anyways much of what she told you to read is, in my opinion either wrong - even many of my Christian friends say that God is not 'clearly seen and understood': or more to the point out-dated or open to interpretation as Alexander Sextus points out above. I wouldn't pay overly much attention to it.