I have a colleague who backstabbed me and ratted me out on a work issue that included us both. Henceforward How do I deal with him in a civil Manner?
You stop using these loaded words for one. He did something you didn't expect. He related information that you would rather he not have related. Or he told an untruth. And you turned it into something. You acknowledge what happened, tell him what didn't work and ask him how things occurred from his side.
Also, if he “ratted you out,” it sounds like you were engaged in activity not consistent with the what is expected of you at your job. You can't be ratted out for doing what you were expected to do. That's just relating fact. So you step up and take responsibility for not being completely responsible about doing your job, and you create a new promise, and live into it.