2.5 year old screaming all night

[Nousername2015]

We've all been up since 3:45 and I'm out of patience and ideas. 2.5 year old has taken to waking screaming in the night and it can take hours to get him back to sleep. He weaned off his dummy over a month ago and has since dropped his nap (although we will let him sleep if he wants to). Bedtime routine has been bath, 1 cbeebies programme on the iPad with milk, teeth then 2 books in bed. We have to stay until he's asleep or he kicks off. In the night it's pure defiance, asking him to lie down gets no, asking him to go to sleep gets a no etc. Tried sitting there quietly but that makes the screaming louder. I don't know what to do, we're all shattered and VERY irritable, help!
For full disclosure we can't bring him into our room as we have a 5 month old who co sleeps from the early hours.

Sounds over tired.

Dropping the dummy will be the cause of the lunchtime nap being dropped, rather than the nap being dropped because it's no longer needed IYSWIM.

The drive to go to sleep is lower in the daytime, so it's more difficult to get to sleep even when tired. The same is true of any night time wake ups. So having extra help to get to sleep is usually necessary.

This is why it would be a better idea to wait until daytime naps were dropped then drop the dummy. Not the other way around like you did it. I would bring dummy back (in fact I wouldn't have removed it yet) and so re-establish daytime naps. It will solve your nights because toddler will be less over tired, and also make bedtime much easier.

Then when daytime naps have completely dropped naturally and DC is sleeping well overnight (with dummy) while not having any sleep in the daytime, then lose the dummy.