loosing hours once employer found out I'm pregnant

I have been working in a Dr's office for 5yrs-32hrs a week with no benefits. Last Tuesday I told my manager about the pregnancy. She said she will help me by getting medicaid by reducing my hours to 20 a week and i said maybe i need to leave my job in the future. This must be in a letter and signed with a termination date. My evaluation was never done in august and she decided to lecture me on how forgetful i am and how my insurance phone skills are still weak. Wednesday she asked for the letter I did not give it to her she told me to go home 3hrs early. Thursday she told me to leave early again. I told her my decision and im do not need Medicaid. I have decided to work my regular 32hrs since I am healthy and let the board of social services decide my insurance details. Friday she told me to leave 2 hrs early because there is no work for me do. Apparently I'm updated with my work. Office manager is Dr's wife, we are considered at will employees.