We've talked about two different ways to show conflicting emotions in a character, so now let's discuss a third way. You can call it exposition or descriptive narration, but it is nothing more than telling instead of showing.
When we tell something, as writers we often have a tendancy to go overboard with flowery language or fancy phrases or overdone metaphors. We need to rein in those impulses and try to make that kind of narration only slightly more formal or figurative than the style that the rest of the story is told in.
Let's go back to the story of Jane and Kathy. We left them in the library, where Jane decided to become friends again with Kathy, even though she still had conflicting emotions of trust and doubt. Suppose we told that scene in a narrative style:
Kathy was visably upset when Jane found her in the library. After Kathy told Jane that Robert had cheated on her with another girl, Jane felt a small satisfaction. After all, she had known this all along, and had told Kathy, but Kathy had refused to believe her. Now Kathy wants to be friends again. Jane has missed Kathy and wants to pick up their friendship again, but there is that nagging little doubt: can Kathy be trusted not to dump Jane the next time a new boy comes into the picture? Kathy assures her that will not be the case, and eventually Jane comes around. They leave the library with their arms around each other, friends again. Yet, the seeds of doubt and distrust have been planted in Jane's mind, and no matter how much she likes Kathy, the course of their friendship has been changed forever.
It is difficult to show or to dramatize all of the above narrative in terms of action and dialogue. At the same time, no story should have more exposition than is absolutely necessary, especially for kids and teens. Even I don't like to read novels where there is more descriptive narration than there is dialogue and action from the adults.
These are three ways to depict conflicting emotions in your characters. I'm sure there are more. I hope these have been of help, however.