hired part time 28 hours a week -promised full time - after school , bullied to work full time without benifits

My boss promised me that if i went to school and got my 2nd license that she would take me full time. I did and then 1 day after i completed my training at my job, my supervisor put me on full time for the month of July, when i asked her if i was going full time, because i need the insurance for my children. She said no, that she needs me to work this month because we are going to be busy. I declined to work the extra day and she said that if im not going to be flexable for them when they need me that when the time comes for the full time position to be filled i would not be the one to get it. Can she bully me this way -