Watch how motorcycle racers corner. Finding their braking marker, turn in, how to look ahead, plan, apex, etc. Then go out and practice the same thing at your comfortable speed. After a while, you will improve.
I come from a motorcycle racing background (I did a 24 hour race in December), so the transfer to pedal bikes was easy for me.
https://www.redbull.com/us-en/triathlete-gwen-jorgensen-descending
I see some crit racers in my area doing laps around a small city block or neighborhood to practice taking corners. I crashed badly last year and Iām still feeling freaked out when Iām descending over 40mph.
Lol, thereās not much opportunity for +40mph where I am now 
The riding errors applicable to motorcycles apply to bicycles too.
This book is a great help to identify and correct those errors.
Good topic. I think the fear aspect is real, and maybe the biggest thing. You have to have a certain willingness to take risks, or at least push that rising fear down, to go fast downhill or in corners. In my case, especially during races, I might be nervous on descents or certain corners, but if something comes up suddenly, where I donāt have time to think about it, Iām a good bike handler. Another example is in crit corners. It takes a fair few laps to get comfortable, and I even got dropped early last year, but a few races later my pedals are heavily scraped from pushing it through those same corners.
a classic right there for motorbikes, but i did attempt to be more conscious of countersteering on the road bike and it definately feels wrong, when you consider the body is the heaviest component compared to riding a motorbike where the majority of the weight is under you
The thing that improved my descending the most was forcing myself to pay attention to where my weight was. Obviously, weight on the outside foot, but the other ātrickā was to consciously put more weight on the inside hand.
I now think about dropping my inside elbow, and consciously think about the inside hand. That puts me in a better position, and when I do this mid-turn, I suddenly find that the corner seems a lot easier and my bike WANTS to turn more.
Have a listen to this podcast Speed with Cal Crutchlow
Whilst not āin-depthā, itās an interesting conversation between Geraint Thomas and Cal Crutchlow with regards to speed, descending and cornering.
There are a couple of swears so itās not work or child safe 
Iāll check it out in a bit. But I can remember in a descent G going off 3 or 4 times in a row and looking a right nervous descender. Hopefully it explains how he overcame that 
They talk about a whole range of things. I didnāt get the impression that either G or Cal were claiming to be the Bees Knees when it came to descending.
Cal Crutchlow crashes a lot, so mehā¦
Consider going up in tire size (going up to even size 32 wonāt be bad at all on rolling resistance). Also I agree with some posts above about dropping PSI. Easier to do if riding bigger tires and even going āTubeless Ready.ā
Also, like Amber says - put that outside foot really freakinā hard down
I understand the technique but as I mention in my initial post is that after my fall I have that fear for the next even a few months.
usually, it manifests in a way that at the beginning of the corner (when I stop braking) I āfrozeā a bit and then want to start braking or just lean back and then my technique goes really badā¦
Iām still not great at twisty descending but going tubeless has psychologically helped me on corners 
At the pointy end of Moto GP racesā¦ so meh to your meh 
Cal Crutchlow is still a great rider, abviously better than me, but i do like his style, but meh meh meh 
I am not a great descender by any means, not enough practice. But I will absolutely second this advice based on a recent experience. I had to wait at top of a climb in misty rain for a long time and was frozen by the time we started the descent. To make matters worse, it was a chilly day and top part of the descent was in the cloud while bottom was dry/sunny but still cold. Because I was so frozen, I was absolutely stiff and shaking ā¦ that made for a ridiculously hairy descent. I was the opposite of relaxed and felt myself that way, but couldnāt change it as I was frozen ā¦ anyway, relax!!
I agree with those who say relax. Iām not a great descender, but am improving, and found it definitely feels quicker when I leaned to let the bike move freely beneath me - almost like an oversized BMX!
A couple of other subtle little things Iāve found help (though possibly not ideal in a group). As youāre riding along a straight, flat section, let the bike shift sideways back and forth beneath you, and get a feel for how you can move your weight and tyres somewhat independently. Itās something thatās innate to cycling, but just more consciously think about it, and how your tyres are gripping.
I also found the recognition on the road that, unless youāre really pushing it, you can correct your line (unlike on single track). So donāt initially focus on the perfect line, but a slightly more relaxed line, and then try to tighten or speed it up, knowing you can always revert to more relaxed line. Having a level of escape available helps mentally. These bits helped me on road, even if off road Iām still a quivering coward!
All kinds of advice youāll have to ecide what to follow but the Crawl Walk Run paradigm is solid. More IMPORTANTLY BE CAREFUL! Bike vs Car, Car wins. Blasting down open roads is risky so Stay Alert Stay Alive! Push it on race day when the roads are closed and you can fly down the mountain like Pitcock