Please Help!!!

I am having a dilemma that has me sick inside. I worked for a company for 6 years,(my second nursing job). Through the six years there were many issues with one supervisor, and she could do no wrong. She was a liar and many nurses quit because of her. The DON believed everything she said, and if she found something wrong, she would blow it out of proportion, pick someone to blame and run with it. Anyway I had several run-ins with her, as did so man others. I couldnt quit my job though because I was a single mother at the time, and it worked out for me. Last year I got married again, and got pregnant, and the nightmare began with my job. I was unable to work as much, and had to change shifts due to health reasons, and they just began to nit pick at everything, accusing me of things that I didnt do, etc..I had no defense, and every week, I didnt know if I was going to have a job or not. Anyway, I could tell they just didnt want me there anymore, and were going to make my life a living hell.My DON and I had a falling out. One of the CNA's called me and told me, "they have it in for you". I decided to give my resignation, because I just couldnt take the stress anymore with my pregnancy. Anyway, my DON called me and left a message on my machine " I got your resignation, and you dont need to finish out your notice. The record will show that you left here on good terms". Well since then I have had my baby and two weeks ago began the job search!!!! To my horror, I have been hired on the spot at 3 places, and drug tested, etc... only to get no return call, after my reference check!!
This is my only reference that shows my 6 years of experience. It seems I am going to apply everywhere and not get a job. WHAT CAN I DO??? I have nothing under my belt. Everyone tells me, "she wouldnt do that to you". Well obviously she is, because I was even given my rate of pay, etc...and then no further contact by the prospective employer. I am so scared I dont know what I should do. I have another interview Monday, and I don't know what to say. Should I tell them about my boss and the way I was treated. Should I not say anything negative?? CAN SOMEONE PLEASE HELP ME AND TELL ME WHAT I SHOULD OR SHOULDNT DO????

Thank you,

Chrissy