Hi Krew. FYI you don't need to make a starter with dry yeast - it has plenty of cells already. Liquid yeast generally does better (is healthier, and thus makes better beer) if you make a starter with it to increase the number of cells.
Secondly, the way you make a yeast starter is not with water and sugar, but by boiling water and malt extract, cooling it, and then pitching your yeast into. For more detailed instructions, look at www.mrmalty.com
Rehydrating dry yeast before you pitch it into your wort is a good idea, but all you have to do for that dissolve the yeast in some water. No sugar or other fermentables needed.
As for your starter, the only thing I can think of that might have harmed your yeast is if you poured the hot sugar water into your yeast, the hot water may have killed the yeast. It depends upon how much hot water, how hot the water was, etc.
You can't go wrong with pitching your US-05, great yeast and if you just pitch it directly into the wort, no starter, it will do a great job.