starting again - the nightmares

how do I stop these

difficulty sleeping as it is, right now, because of some disturbances in my life re: my mother and her psychosis (and a string of problems because of this)

so I wake middle of night, me stressed, finally get myself back to sleep, with the horrible nightmares that follow

the one this early morning was a roomful of women, merrily choking me

how do I stop the nightmares?