You see, it's her reality. She believed that she's ugly, she knew that, she knew that confidently. Sometimes when people tell you one of their realities, you should know that it's not helping to just deny what they are saying. Saying, "No, you're beautiful..." or, "You're wrong!" even if it's true in your reality, it's not true in the person's own reality. It may work sometimes, aided by a couple other factors. This is also why comparing problem, "my problem is much worse than yours," will only make the person feel bad about him- or herself. So, if you want someone to believe in something, to believe in him- or herself, to be believe that it's his or her reality, then make one. Make what you say a reality to the person, by strengthening the reasoning with something that she feels important and powerful.
In this song, she was finally able to have altered her reality in which she now believed that she's beautiful. Why? Because God was an important figure in her life, and she learnt that God never discriminated anybody, for God, everyone was beautiful. If God was down here on earth, she knew she'd be able to face Him feeling strong, without the feeling that she might get judged by her own appearance, like other people did on her.
Carl Rogers, one of the founders of humanistic psychology, believed that people get their realities by experiencing them in the past. the experiences are deeply rooted in their system that they become, well, their realities. Rogers asserted that helping professionals should hold to the first cardinal rule, which is to accept the perception of the person unconditionally, which is why when you want to listen to other people's problem, empathizing is something you should do. How can a person feel better when all you do is, "You're being a crybaby. Move on already. Come on, your problem is so small compared to mine! You think it's hard to lose a friend? Try me, I might marry a jerk out of my family's force..."
Having to marry someone you don't love is not worse than losing a friend, and vice versa. The problem is a problem according to your own book, according to your reality. This is very important to remember if you want to be a good friend, a good spouse, a good family member, or even a good helping professional. What you have to do is to accept the perception of that person. Then, without being directive and suggestive, you can help the person realize that there is another reality in his or her life. A reality that helps the person build a better life. Remember this your whole life.