Brandi Means listens to a video of Trevor O’Brien singing on Friday at her parents’ home in Gillette. O’Brien, who had lived with Means’ family for years, died by an apparent suicide March 8.

The bullying started in seventh grade. Crystal Haukaas noticed her son, Trevor O’Brien, was being singled out by other kids. He was gay in a coal town, and his mother knew it before he did. When ...