I accidentally plagiarised a student paper (2%) and I am terrified (pls read context)

Basically I have an assignment (computer science) that asked for some examples of some syntax/how I would implement an idea using a syntax example. For those that do not know what I mean, this is something in programming that is used to do things like declare objects, kind of like the start of an instruction. Each programming language has its own syntax and syntax rules.
I was trying to do syntax for REST architecture. My lecturer had given an example from a previous student essay. I spent hours searching for the syntax for this particular answer but could not find it aside from in this student essay and assumed that, like other programming languages, that the example he gave was generalised, used everytime anyone wanted to do the specific operation.
I submitted the paper, but now I have a plagurism warning. I am so scared, it seems I was wrong and I have directly copied a student's work that does not apply to my work. I spend almost four sleepless nights trying to perfect this whole project so im freaking out man
Could i email the lecturer and say I forgot to citate it? I edited it slightly so the urls in the example were mine rather than the previous student's, but upon reviewing I also noticed I forgot to change one so i think im screwed. What will happen??? Honestly in so freaking done, if i get done after all this i might as well stop everything i tried so hard
sorry if you dont understand what i mean, ill try and explain more if people ask. also sorry if i have posted this in the wrong area I cant figure out how this website works rn im seeing double because I havent really slept much lol

Basically I have an assignment (computer science) that asked for some examples of some syntax/how I would implement an idea using a syntax example. For those that do not know what I mean, this is something in programming that is used to do things like declare objects, kind of like the start of an instruction. Each programming language has its own syntax and syntax rules.
I was trying to do syntax for REST architecture. My lecturer had given an example from a previous student essay. I spent hours searching for the syntax for this particular answer but could not find it aside from in this student essay and assumed that, like other programming languages, that the example he gave was generalised, used everytime anyone wanted to do the specific operation.
I submitted the paper, but now I have a plagurism warning. I am so scared, it seems I was wrong and I have directly copied a student's work that does not apply to my work. I spend almost four sleepless nights trying to perfect this whole project so im freaking out man
Could i email the lecturer and say I forgot to citate it? I edited it slightly so the urls in the example were mine rather than the previous student's, but upon reviewing I also noticed I forgot to change one so i think im screwed. What will happen??? Honestly in so freaking done, if i get done after all this i might as well stop everything i tried so hard
sorry if you dont understand what i mean, ill try and explain more if people ask. also sorry if i have posted this in the wrong area I cant figure out how this website works rn im seeing double because I havent really slept much lol

I honestly wouldn’t worry. 2% is so small. At my uni it was only if it was a significant chunk (like 25%) had been copied because most things you submit will likely have familiarity to things already published/ submitted and this is what gets flagged. If they ask you about it you can explain yourself, or you can email your lecturer if you would feel better about it. They likely won’t do anything serious if they do bring it up to you though if this is the first time this has happened. You would likely get a warning.