I'm guessing it was her you were reacting to, not ghosts.
This bit: "I even woke up one night choking and in my nightmare I remember I was being choked by something which I didn't know what it was." I used to get the same thing - waking up in the middle of the night terrified, paralysed and unable to breathe. Sometimes I'd wake up and it would take a minute or two before I could breathe again so I'd be gasping when I finally could. It's called "night terrors" and is not uncommon:
http://www.nightterrors.org/
http://en.wikipedia.org/wiki/Night_terror
I had them for about 6 months arpound the unhappiest time in my life, haven't had them since.