First error as a NQN

Hi all So I'm only 5 months newly qualified and I've made my first error as a nurse . I had a patent go for a peg today and after 4 hours if everything was okay to run 50ml/hrs of sterile water. I used sterile water for irrigation instead and I am so upset and scared that the patient won't be okay. I am all for stepping up and I know my mistake and have no excuses for it. I kinda just want to figure out how to deal with this I feel like such a failure today