I can relate. I was a polysubstance abuser with multiple ODs and a serious benzo and booze habit (17 years booze, 10 Xanax). When I went to rehab I was cut off of everything, needless to say had excruciating benzo withdrawal. I had siezures for a few years - truly hell. There were days when I literally couldn't remember my name, and my nerves were so damaged I could have anything touching me so I stood around my house naked because any skin contact or pressure gave me a horrible electrical current underneath my skin. My anxiety was out of control and constant. Withdrawal and PAWS continued to get progressively worse until about month six and then plateaued, and started to improve around a year and a half. I was incapable of taking care of myself because I had zero short term memory (almost burned the house down cooking dinner - started it, got distracted, came back to a fire). I can relate to what you're going through.
It takes time to recover, but it does happen. Talk to your doctor about the below list before you actually begin to take anything. Go get a good multivitamin (Garden of Life), magnesium in a bioavailable form (magnesium taurine won't give you diarrhea, citrate or oxide are good but will give you diarreah) - magnesium helps keep your muscles relaxed and helps diminish the electrical sensations and also helps to regulate your heart beat, get some 5-htp, Relora (helps with anxiety), trazodone (helps with sleep, it's an antidepressant, doesn't feel great but it helps), and get some Indural (propranolol) a it's a nonaddictive beta blocker that will lower your blood pressure, help with heart palpitations, and stop the adrenaline response with anxiety so you the attack doesn't phisiologically affect you. You will need a prescription for trazodone and Indural.
During this time it is imperative that you eat enough healthy fat and protien as that is what your body requires to heal the neurological damage that is taking place. You are currently suffering from excitotoxicity with which glutamate is not regulated properly so it is destroying your nerves. It's hell on earth but once it runs its course you will start to get better, however, don't be surprised if you continue to get worse before it gets better. When you feel bad or low about this keep in mind it is temporary. I know what you mean when you say you lost 45 pts from your IQ - this is not permenant, your intelligence, memory, and cognitive function will return.
I started to notice marked improvement around the two year mark. It hs been a little over six years since I quit benzos and I am about 80% - 85% recovered, and notice more improvements everyday. My senses are still super sensitive (light, sound, touch), but I have learned to live with that and they do continue to get better. I do have gastrointestinal issues that I struggle with and hope they get better over time. My anxiety is at an all time low post benzos (prior to benzos I didn't really suffer from anxiety), and my depression seems to be situational now, and not an underlying pervasive cloud of doom. Ironically, I get the best sleep now than I ever have outside of childhood.
I hope this helps. Feel free to hit me up with specific questions or if you're frustrated or depressed and just need to vent. I am so sorry you are going through this - the medical community really should be more knowledgable and useful when scripting benzos or supporting somebody that is coming off of benzos. I wish you the best!