Walgreens Mrs. Jones Discrimination towards a pregnant woman Chicago Illinois

I'm a service clerk at Walgreens and before I went on Maternity Leave my boss and I had a verbal agreement that I will be able to resume my schedule. She told me let her know when I have my child, and the date of my return. With 5weeks gone past I wrote her asking can I return to work. She ignored me for four days, and finally wrote and told me she hired someone else, her hours were cut, and I wouldn't be able to come back. My problem is if her hours were cut why did she hire someone else AFTER I contacted her to get my job back? Why didn't she take hours from all employees instead of taking all of mines? And lastly, why guarantee me a schedule she never intended to give back? I know for a fact her decision wasn't based off my work ethics, but simply because I'm friends with an employee she doesn't like. She mentioned to a co-worker she would "split us up", and I believe her not letting me back is her way of doing so. Even during my pregnancy she treated me like s**t. When I couldn't stand any more due to my swollen feet she gave me crates to sit on which increased my back problems, and even told me to stand when certain people came in. Her STL threatened to "beat me up" while I was pregnant, and even sent out more threats in front of her, and since they're friends she did nothing about it. In my heart I know I've been treated unfairly, and I want something done about it.