In the first example of showing conflicting emotions in a character, it was done in two or more scenes. Let's talk about how to do this in one scene. You've already set the stage for the relationship between Jane, Kathy and Robert. So now you have Jane angry at Robert for two-timing Kathy, and angry at Kathy because she won't believe what Jane says, and she dumps Jane as a friend. Some time later, Jane finds Kathy crying in the library. She feels sorry for her, goes over to ask what is wrong, and discovers that Kathy has finally realized Robert is two-timing her. Kathy now wants to make up with Jane and be friends again, but Jane is still hurt and angry that Kathy didn't believe her and dumped her. She wants to be friends again but she doesn't know if she can trust Kathy not to dump her again if a new boy comes along, and she still feels the hurt. What does she do? They talk, and finally Jane agrees to be friends again, even though she has the conflicting emotions of doubt and trust. They leave the library together. One scene, one problem, one resolution, two conflicting emotions.
Stay tuned for the third way to present your character and her conflicting emotions!