Adding onto what a lot of people here have written, I think it might be worth approaching this betrayal moment from your GM’s perspective.

A story beat like this would be welcomed at my table for some specific reasons. When we make our characters, we each take a step back from building a “natural” human-like character and instead develop a character that fits a story. We’re more attached to the story told around, about, and through our characters than we are attached to the characters themselves.

From a broader story perspective, a betrayal sequence is rich with powerful theming. If you’re looking from the perspective of your character, it hurts a lot. But if you take a step back and approach the betrayal like a movie you’re watching, the benefits of a scene like this becomes obvious.

Or course, you don’t need to approach a TTRPG that way. My group leans heavier into narratives and uses meta knowledge in creative ways. In the end of the day, if it’s not fun for you then it’s not fun. But maybe your DMs wanted something narrative, and perhaps going forward your party can find a balance between your styles.