What can I use for dry, damaged, frizzy

First of all, if you haven't already, stop straightening. 

Then, condition your hair every chance you get and rinse in cold or lukewarm water.  I like to use pro-vitamin E split end serum after I wash or condition.  It contains some silicones, which aren't good for most hair, but before those it has some really good hair vitamins. Brushing with a boar-bristle brush might help too if you don't already, because it helps distribute natural oils all around your hair.

Keep doing this for awhile, and your hair should improve.  But if it still seems damaged after a while, I would suggest getting a trim to remove the damage and keep your hair healthy.