Best advice - enjoy it. Cupcakes and sweets can be part of a healthy lifestyle as long as they are consumed in moderation. I do better with sugar kept few and far between because I know that once I start adding sugar, I tend to crave sugar more and when I don't eat it, I don't want it.
I went through the same feelings of guilt when I first started changing my habits and they are hard to get past mentally. Realizing that it's the complete lifestyle and not just the "can't have this or that" diet mentality will help.
Great job on your loss so far - and keep it up!