In the summer, I took a math course where one of the homeworks involved a question where answers were expected to include several diagrams alongside an explanation. At the time, I thought it was a difficult question and I had been complaining about how confusing it was to a friend who was also taking the course. Eventually, I did complete the question independently with some suggestions the instructor of the course gave me during a meeting.
Before the submission deadline, my friend offered to explain to me some of his ideas about the problem over social media, I believe I had asked for this a few days before because I was struggling. At this point, even though I had already finished the question, I agreed to the proposal. I thought there would be no harm because the course permitted collaboration to the extent where students can discuss their ideas about the problems in the homework. My friend proceeded to send me some diagrams alongside a very brief explanation outlining his steps, at first I went along with this because I did not sense anything wrong. But after it seemed like they were sharing too much, my friend stopped after I requested that they not continue their explanation (I was afraid that if I did not stop them, I would have essentially seen their solution to the question).
When I submitted my problem set, I did not modify the answer I gave to that specific question prior to the conversation, and so what my friend showed me had no effect on what I actually submitted. Thus, I did not copy anything or 'cheat' in any obvious way. Still, I felt very guilty and anxious because I thought I had seen "too much" of my friend's work. I tried to forget about all of this and assured myself that the correspondence was harmless because it did not influence the work I submitted. Nevertheless, a few weeks later, after something reminded me about what had happened and I decided to e-mail the professor with a description of what happened on two separate occasions. This was after I discussed how guilty I felt with the friend I mentioned earlier, who respected my decision to send the e-mail.
I think my instructor missed both of these e-mails. After this, I had once again decided that I should just try to move on, because once again, I convinced myself that what happened was harmless (as I said before, I did not change my answer to the question even after seeing what my friend showed me). All of this happened a few months ago. Once again, I had resolved to just forget that all of this happened.
A few hours ago, something had reminded me about that conversation. I decided, for some stupid reason, to review the conversation again, and I once again felt a wave of anxiety after reading it. I regret that I did not send a 3rd e-mail earlier so that my instructor could provide their input on this situation and give me some peace of mind. Furthermore, the final marks for the course have already been released and finalized, and I feel like sending an e-mail to my instructor about this issue at this point would either seriously annoy them, or put them in a very bizarre position. I do not know what I should do in this situation, or if I am just overthinking things.