Net Friend torturing me to death

i am a 23 year old working woman. I have Compulsive lying disorder which i think is developed because of my complex about my poor looks.
i was going through a bad patch of my life where i didnt have any job. i then started writing on a site and met a girl much younger than me. we became friends and eventually we shared our numbers and mail ids.
i realised that she is extra sensitive and well beyond her age. i had lied to her that i am 25 at that time and i am married to the most wonderful man in the world who loved me for who i am!
she started calling me mom and my (imaginary) husband papa.
we used to chat daily and became aware of each other's problems.

then i got a job and eventually i told her who i really am. i shared my work email with her as well so that she can reach me as chatting daily was not possible for me.
she cried in the beginning but came around and accepted that the person she called her mom and got involved with is actually a mentally sick person.

i started caring for her as well. whenever she had problem related to her school or parents, i listened to it and tried advising.

meanwhile i fell for a guy and i told her about it. this guy flirted initially and then backed off.
i was devastated. she heard my problems and advised me to move on.
i could not.

problem with her is her mood swings. she sometimes is very happy and cheerful and will make me feel good but sometimes she becomes really dark, she sends me messages saying that i used her and that she will commit suicide. though we have never met her in my life, i cant take such messages lightly. everytime she accuses me or sends me such messages, my BP goes high, my legs tremble, i think i made the biggest mistake of my life by befriending her. i can not see her harming herself for me or for anyone.
she is lately acting very strange and i am scared that she will really harm herself.
on some of the occasions, she called me up saying that she has fled her house and has come to my town to meet me, even that had me panting cause i was scared of her security in a town like mine.
later on i realized that she was kidding.
there are many things like this which freaks me out cause i think she will one day commit suicide and blame me for it and then my life will be ruined.

i want to tell her that just like me, she needs medical assistance for her extreme mood swings.
i want her to stop sending me such messages cause that affects my health very badly.

she says she now wont be able to trust anyone anymore cause i deceived her.
i know that i did but that was true as far as my identity goes. i really cared for her but to no avail.

if my parents get the wind of all this, they will throw me out.
what should i do?
she has my number, my mail, my work mail which can give her my office address.
i can not share this with anyone as i will have to reveal my sickness to that person as well.
i feel trapped.