Is It Ever Okay To Cheat?

Is there ever a time that it's sort of, a little tiny bit, make an exception, turn a blind eye and cheat?? I have been struggling with this question myself. Last weekend, I worked on my homework on Saturday and Sunday being careful to do a really good job, striving for that 100. I felt good. I had read and re-read the chapter, I had studied and knew my stuff. I got to class on Monday morning (different class than I usually am in because of the kids being sick with the flu and my gracious parents being able to miss work to watch them for me) :) and everyone is talking about HW chapter 38. Well hell, I had done chapter 35! shit! What to do now. UGH!! My face got flushed. I was feeling so hot, and for some reason tears welled up in my eyes. I couldn't believe that I had worked so hard on the WRONG homework! I was upset and disappointed and so frustrated with myself, and to top it all off, I was going to get a ZERO! Great. That will average in so nicely to my GPA. I just felt like giving up and going home. The girl next to me Erika, so sweet as she was, said, "do it now. you have a few minutes. try, it wasn't that hard" but I hadn't read the chapter at all, I had no idea what any of it was, and at that time, I couldn't think. My head hurt, my throat was burning my eyes were holding back tears, and I just was so upset. She slid her book closer to mine and said "here... "
I looked around the room. I looked at her. I wasn't sure what to do. I felt this horrible tug-of-war in my head, should I? shouldn't I? What was the right thing to do? It wasn't like I had just not done the homework, it wasn't like I hadn't worked my butt off, but it was my responsibility to make sure I did the RIGHT homework, and I hadn't... what to do, what to do??
I said "thank you so much. I owe you!!" and I copied. I got a 90 and not a zero.
I'm still so unsure how I feel about this. Cheating is cheating. Cheating is wrong. way wrong. BUT, for some reason I can totally justify it in my head. I have three sick children at home. I did do my own work, just the wrong work. I hadn't been slacking, I just made a simple mistake, I wouldn't cheat just because I was being lazy or on a test or quiz or anything like that. It was a homework, it was semi-wrong to do, but I haven't done it before and hopefully will NOT do it again.
So then the battle that begins inside me now is why don't I feel so horribly wrong for cheating on my homework?? Why can I sort of justify it to myself? & How do I ever really thank Erika for saving me all that self-anger and frustration??
I did come home and read chapter 38 ~ did the questions myself and studied it all... I Aced the test on it too. I did put in my time, I just didn't do it at the right time. ~ I did learn a lesson, that I have to double check my calendar to make sure I'm doing the right homework. And, honestly I really triple check it and sometimes more, and made a list in order of the homework chapters I have to do and triple checked that too!
So do you think there is ever a time when cheating is okay?