If Catholics really put so much stock in the very words and teachings of Jesus, then why do they ignore the Beatitudes where Jesus taught that if you lusted after a woman, you committed adultery in your heart, and that it's the heart attitude that is what counts, not merely keeping the letter of the law.
Don't forget that hating your brother is equivalent to murder.
So while Mary may not have physically murdered someone, if she lied, hated anyone, whatever, then it's the same in God's eyes as doing the sin.
would that equate with Jesus being angry with the money changers and tipping over their booths and throwing them out of the temple???
How is sinlessness of Mary ignoring the Beatitudes? Indeed we teach that her sinlessness is absolute; but the point remains that romans 3 cannot be taken literally in general, and neither that "all" in the middle of it.