From what you say, it sounds like your cousin has a problem that she doesn’t even realize she has: a problem with pride. I couldn’t help but think of Jesus’ words in the Sermon on the Mount: “Why do you look at the speck of sawdust in your brother’s eye and pay no attention to the plank in your own eye?” (Matthew 7:3).
Your attitude isn’t surprising; I doubt if I’ve ever met anyone who likes a hypocrite. A hypocrite claims to be close to God, but in reality, is far from Him—and shows it by the way they live. The tragedy is that hypocrites often don’t realize just how far they’ve drifted from what they ought to be, and they become proud and self-righteous. Some of Jesus’ strongest words were directed at those who claimed to love God but denied it by their lives.
Instead of avoiding your aunt, however, I hope you will try to help her. Only God knows her heart, of course — but down inside she may have a sincere faith and a genuine desire to do what’s right. Pray for her, and ask God to give you an opportunity to confront her—lovingly but directly—and let her know how others see her.
Most of all, don’t let her attitude keep you from Christ. God loves you, and life’s greatest joy comes from knowing Christ and living in His presence every day.