I feel like I am going insane!!!

I definitely agree with you in all this but it was pretty little of you to sink to her level. There could have been other ways but it's just for the best that you told her straight off how you felt. You DID have the right to tell her how you feel and so you did. She was the one who did not have the right to treat you the way she did. After how much you helped her through everything and then she backstabs you. You're much better off without her stressing you out all the time. I think you did the right thing and i commend you for being the bigger person overall by trying to talk reasonably about it.
-A

"I met this girl 3 years ago in a self-esteem course I took. For 3 years I have been catering to her."

It appears that on the surface you didn't get much from the course. It does seem that, on the other hand, you have learnt what you needed through this experience.

Close the book and move on. She obviously isn't worth either time or attention.

Bert

Seems to me both you girls should be old and wise enough to know when to cut your losses and walk away from a situation really...

Have some sense think of the example both of you are setting for your kids behaving like your 5 yrs olds yourselves...

Sorry to be harsh but thats the reallity of it