Aaagh, don't sit there you will be held prisoner for ever! Believe me, I have been there and KNOW this.
My dd at 16 mo was like this after going on holiday where she had slept in our room. This awful behaviour went on until she was 20mo. She was knackered, we were knackered, it was awful, but she did improve.
Cc is awful and too upsetting. This is what we did, it took about 3 weeks but it did work fanatstically, and the first improvement was settling in the evening at bedtime, the night time took a bit lonbger but it all came togethr in the end.
Put her to bed, kiss her night night and leave. She will cry straight away. Go straight back in, lie her back down, leave and shut door. She will cry, go straight back in etc etc etc. This will happen many many times, too many to count. Repeat through all waking up at night as well. Don't give up after about 7 days when you think it isn't working, because it will.
My dd is stubborn and strong willed, that;s why she took so long, most children improve within a few nights. I could write books on this, it took us so long to find a gentler method. After about 2 weeks of this she was waving bye bye at night time and settling (middle of the night wakenings were still happening), but we could see the progress.
Hth xx