Quitting nicotine caused me to crave sugar, too. Based on what I've heard and read, that's a near universal response.

I knew that the sugar/nicotine cravings would eventually fade, and that in the long-term getting off nicotine was more important than avoiding sugar, so diet-wise I just did whatever was necessary. If that meant eating a couple of Snickers bars, that's what I did.

My advice to anyone in your situation would be to focus on overcoming the nicotine addiction and otherwise just do the best you can.