really feel for you. my advice would be that controlled crying is about leaving them to cry for a short time eg 5 mins, going in, doing whatever it takes to comfort, including picking up. once settled and calm, put back down and leave to cry (if crying starts again) for the same amount of time as before plus a small increment of anything from just 30 seconds extra if dc seems to be getting hysterical, to 2-3 mins extra. repeat process, adding small increments of time each time that you leave them.
So:
DOwn in cot, say night night, leave room. 5 mins of crying
Go back in, comfort, put down, say night night, leave room, 7 mins of crying
Go back in, comfort, put down, say night night, leave room, 9 mins of crying ...
This gives the message to the dc that they will get comfort but at some point they give up waiting for it to come and wear themselves out ... rather than crying and crying and crying for ages and you feeling worse and worse the whole time.
It works for me, I have used this technique on several occasions and it takes 3-4 nights at which point ds has just gone straight to sleep when put into cot. BUT all children are different and it may not work for yours. I had enough steel in my soul to do this but not to leave him simply until he just gave up - couldn't bear to leave him for 10+ minutes, and would never leave him for 30+ minutes or hours, as some people do. Absolutely NOT judging anyone who does this, it is about what you can take and what your dc respond to. Main thing is to be consistent and once you've started down a course, stick with it for several nights in a row.
HTH