My hair is an overprocessed shitshow too. And broken off in places. I am so, so cross with my (now ex) hairdresser.
If you can get Olaplex 2, do. Otherwise, use the Olaplex 3 at least once a week.
My routine is finger comb any knots of out hair, then comb hair with varnished wooden comb (no brushes, nothing rough). Wash hair with shampoo for damaged/dry hair. I'm using Shwarzkopf Beology shampoo, which probably isn't available there since it's for the Asian market, but if you see it, it's good. Agitate your hair as little as possible while shampooing. Then, instead of conditioning, I squeeze the excess moisture from my hair, and liberally apply a hair mask. I'm using one from Ryo, but again, I think this is only available in Asia. I was using Aussie reconstructor, but it's shit. You need the thickest, buttery-est mask you can get. So thick it's practically a solid. It's probably full of silicone, but good, because our hair is wrecked and it needs all the coating it can get. 
Then, I gently comb the mask through my hair and wash it out. I only rinse downwards, if you see what I mean. No agitation, no swooshing the hair around so it might tangle again.
I blot my hair with a towel. Again, no agitation, just squeezing, and the softest towel I have. Then, I put ten pumps of Ryo hair oil in my palms and run it through my hair. There's an OGX argan oil which I also like, but it's hard to get here. After putting the oil in my hair, I comb through and leave it to air dry.
Once dry, it seems normal. Soft. Obviously the broken bits are still broken, but they're not obvious.