Welcome!  You poor dear.  

Stress and the flat iron are probably BOTH causing problems with your hair.  

The flat iron heats the hair, which removes the moisture from the hair shaft.  This, in turn, makes the hair, dry and brittle.  If you can eliminate the flat iron, I'm sure your hair would appreciate it.  

Adding moisture to you hair, via conditioners and/or oils can also help the condition of your hair.  Be careful of shampoos and/or conditioners that have lots of ingredients that end in -cone.  These can build up on your hair and actually cause more brittleness with time.  If you do use them, try a clarifying shampoo from time to time to remove the build up.  A vinegar rinse can help if the build up is not severe.

Let us know how your hair does!

sorry to hear about your hair

My hair has experienced the same exact problem, my hair was sooo healthy and shiny, until i got depressed (family stuff), then i started using the ceramic flat iron to smooth out the damage, which obviously made more damage.

I started using jojoba oil, and like juri suggested doing a CWC helps a lot.

Now i can actually wear my hair loose
Hope Everything goes well, and Good Luck !