the trouble is, that she has learnt that the longer/harder she screams, you will eventually give up and take her into your bed. (totaly sympathy, I understand why)
This means she will be much harder to convince that this isn't going to happen if she keeps on.
The only thing I can think of is to work on this one step at a time.
first. ban her from your bed. She is not allowed into it at night under any circumstances ever. Spell this out to her before bed, make it very clear, as of now, not in Mummy and Daddy's bed.
But it sounds as if going straight to her alseep on her own in her room is too big a step. So I would get a mattress/airbed/sofa cushions and have them ready. When she wakes up, back into her bed. You or dh sleep on the floor in her room. Because your bed is banned to her, so if she needs comfort/help, you will stay in her room, but she can't come to yours. Once she is going regularly back into her bed and going back to sleep, then you begin to withdraw from her room, one step at a time, so first, wait til she is asleep and leave. Then give her 5 minutes and creep out as she is falling asleep, or move to near the door. Then either outside the door, or cuddle kiss and leave.
I would also look at things like a small nightlight, a special teddy that soaks up all the scaries and looks after them so her room is safe. At this age, you do get the rise of imaginative monsters etc, if that is an issue then a water spray which is labelled 'ant monster spray' gently sprayed round to send all the monsters running away, that sort of thing.
But the biggest key in all this is that whatever you choose you must must must stick to it. She needs to learn that you will follow through. Is there something during the day that you could use to get the message over that you will follow through and keep to your word?
And the screaming til they are sick just clean up in silence and keep going.