This question already has an answer here:
Long story short (remember that since that's not the point this is a summary that lacks an explanation for my reasons or detail on what happened, so please go easy on me), I left sick for a while without properly communicating when I would come back, then came back to my office and resigned with no previous notice.
There is an explanation but that's not the point of this thread, although I feel that it's not justified anyway and I feel bad about it. My manager did mention that he was pissed off.
It should be noted that it was a summer internship that was also my first job.
I feel bad about it because it was a nice tech company with a focus on quality that taught me a lot.
I'm also very concerned about potential bad reviews from them, which is something I'd like to take care of if I can.
The point of this thread is that I need advice on whether it's sensible to send a late apology email now, something along the lines of "Hey, I'm very sorry I behaved that way in the end because I was a newbie and didn't really know how to handle certain situations. I feel that I behaved in an unprofessional way and I sincerely apologize. I'm very grateful for the time we worked together and all I learned with you guys." or something like that.
One argument against it is that a friend mentioned that doing that would give them written proof that I did behave poorly and make things worse. I dont know to what extent does that outweight the potential advantages of making things right.