Is my whole roll of film ruined?

I have a nikon n75 and I got some 400TX film for it. Black and white, 36 shots. I put it in and it wound right up, but then I accidentally opened the back again to see it for a few seconds. I did not realize this exposes the film. Is my whole roll ruined, or just like the first 3?

You won't really know until you have it processed. You should probably warn the photo shop about what happened, so they'll be extra careful about opening the camera and removing the roll.

Tri-X is pretty fast film. Hopefully most of the photos will be undamaged, but it's hard to predict.

Live and learn…

Just the part that was exposed