Well done for taking on this puss.
I have a pal living in Spain and the stories I hear are dreadful.
So how many other cats do you have?
One point I'd make is that it can take a few weeks for breeding hormones to finally get out of a cat's system after they have been neutered. She should be a bit calmer in a few weeks or so. But that aside, I can't begin to imagine what she's been through - burned with cigerettes, you say?
I think you have to come to terms with the fact she's been badly traumatised and her rehabilitation will be in terms of months and years rather than weeks.
These types of cats are the most challenging and rewarding. I know she'll have you in tears of joy one day. Try to give her space and time. Time cures an awful lot of hurt....