Don't beat yourself up! Having a low blood sugar is definitely a serious thing and you need to take in the sugar to increase it. You did the right thing ingesting sugary foods to bring up your sugar. Orange juice and peanut butter can be a better option, as the protein will help to stabilize the sugar levels. Learn from this and move on! Maybe (especially if you are new to sugar testing and insulin) setting a timer to go off when you are preparing your meals or before you eat can remind you to check your sugar then, which would prevent this sort of situation from occuring again.