I love your natural hair in the first picture. I can see how you're unwilling to chop off your identity there. I recommend reposting this in the 4a section so that someone with a similar curl pattern whose hair went through a similar trauma might be able to help. How high was the flat iron? I used to iron in the 400 degree zone which is pretty dangerous, especially without a heat protectant. Things that I know are good for heat damage: try some protein treatments to repair and restore elasticity, followed by deep conditioning treatments for moisture. If you're using sulfates still, drop them or limit your shampoo to once a week because that will dry your hair out and you've already fried it. Use a natural sulfate free shampoo and a moisture rich conditioner. You might want a conditioner that has a bit of protein in it now too to help with the damaged hair.
For a protein treatment, there are so many things you could use. Mix a few tbsp of coconut oil (extra virgin is best, I think) with a few tbsp of honey and a raw egg. Maybe throw in some greek yogurt or mayonnaise. Stir well. Apply to clean damp hair and let it sit for thirty minutes to an hour then rinse. You could also go buy yourself one. The aphogee two step protein treatment and the Joico K-Pak are popular.
Also check out this gelatin protein treatment thing that's popular:
Pedaheh's Hair Blog: Science-y Hair Blog Recipes
For a conditioning treatment, it's not too different, minus the protein. I like to mix 1 tbsp extra virgin olive oil, 1 tbsp coconut oil, 1 tbsp grapeseed oil, 1 tbsp honey, then a few tablespoons of a very moisturizing condition (I like SM's restorative conditioner) and then just put that in my hair. Cover with a shower cap and leave in at least an hour. I'll go to sleep with it and shower in the morning actually. You could also just get a very great moisturizing conditioner and leave it in clean damp hair as a masque as long as you like. And there are tons of deep treatments already prepared out there. I just prefer to use what I have on hand because my hair is thirsty and oils are okay when you have thirsty hair.
If you try to repair and the curls don't come back, don't worry. Your hair will grow back, and if you co-wash it and massage the scalp vigorously and regularly it'll grow back fast, healthy and strong. You might want to repost this in the curly men section too. Maybe someone's been in your exact same situation.