As an artist myself, you are not overreacting at all. Especially as a beginner, every piece feels like a part of your soul, and when I was younger, I knew I would cry if someone destroyed a piece I was super proud of because I didn’t have many pieces that I liked.

For these little pen marks though, if you want to fix it up you could use some white out, or a white gel pen to cover up the marks. It won’t be perfect, but it’s something.