The speaker of "would you believe?" is trying to get someone to listen, and doubting that anyone will. Almost every line is a question: if I told you I'm scared, if I told you I'm in pain, would you believe me? The speaker admits to a "lie" in the opening lines, which makes it hard to tell what is true, and that confusion seems to be part of the point. Feelings here contradict each other: being happy and crying are the same thing.
The mood is fragile and lonely. The speaker moves from asking to be believed to begging to be understood, and then offers to show the "hidden world inside my mind," if only the listener promises not to be scared. That request suggests a fear of being judged. The ending is the saddest part. After the flat "probably not," the speaker admits to crying while happy, then wonders whether they were ever happy at all. The poem closes on doubt rather than comfort.