Sleep alludes us all

Mike and I are having a really difficult time with Piper lately.  One night she started screaming bloody murder about a bad dream she had where a kitty cat was attacking me.  She kept saying that the cat was "getting mommy" and that "it keeps meowing at me!"  Then she started saying there were ghosties in her room.  From that point on we have had a horrible time at bedtime and naptime.  We are so exhausted.  It feels like we have a newborn again.  Those first few nights she screamed and got out of bed over and over.  It was after midnight when she finally fell asleep.  We eventually took her mattress out of her crib and laid it on her floor.  Hopefully we can get her a toddler bed soon.  She is going to bed earlier but her bedtime is usually between 7:30 and 8:00 and she is falling asleep around 9:30 and 10:00.  We've tried all kinds of things from spraying her room with "monster spray," to making her bedtime routine longer.  Right now the only thing that works is to lay by her for a bit until she is settled and tired and then sit outside her door until she falls asleep.  If we don't she screams and screams.  She calls out for us over and over and we have to reassure her that we are still by her door.  I thought perhaps I should let her give up her naps but she is not going to sleep any earlier on the days she goes without a nap and she is generally grouchy and irritable the entire day.  On the days that we are just fed up we let her scream it out and it is heartbreaking and we usually find her hiding in our room under the covers passed out.  Once she is asleep she continues to wake up three or four times a night and we have to again sit outside her door until she is sound asleep or she screams and wakes everyone in the house up.  In the morning she is waking up between 5 and 6:30.  Sleep is so interrupted lately and Mike and I feel like we are walking around in a daze all day.  The other morning I was so tired that I thought I'd sleep in and let the boys take care of her. She stood outside my door screaming like someone was attacking her.  "I need my mom!  Let me in!"  On days where I wanted to catch a little more sleep she used to wake up and they would come get her and she would happily go downstairs with them.  They'd turn on a show and get her some cereal or a light snack  until I'd come down and make breakfast.  Lately she screams at them when they try to help her.  Her behavior is really affecting all of us.  She has been so clingy and needy.  I am just praying this is a stage that will pass quickly.  I wish I could figure out what was going on with her.  The boys have gone through brief moments of separation anxiety or night fears when they were little but those were pretty mild compared to this so I'm not really sure how to deal with it.  Being a parent is so hard sometimes when your kids struggle with things that you honestly don't know how to fix and just have to ride it out until the next stage comes.