failure and learning to let go

I just received a scathing evaluation of a project I completed for a professor this semester. He basically implied that my work was useless and the project was an utter failure.
I was very upset, not only because it is probably one of the first truly negative professional reviews I have gotten, but also because I felt blindsided. I tried contacting this person many times throughout the process, and never heard back.

I am not going into details because I am working on letting go and moving forward.
What I have learned:

I am too attached to what people think of me and my work.
I am unable to separate myself from my work; an indictment of my work is also a personal one.
I need to be more assertive and get what I need. (Even if that means being a pest.)
I catastrophize. (This is not the end of the world. My work was adequate for the other two professors.)
My intent and underlying feelings about things can manifest in different ways. (I did not want to take the project. I only took it to allow the class to move forward. Maybe the negative feelings were evident in the end result.)
I am not perfect. I can and will make mistakes. I need to work on processing, learning from them, and letting them go.

I can't stop thinking about it, though. I am working on acknowledging the thought and moving on. If I can't make the thoughts stop, I can reduce their power and hold over me.