Need serious help!!!!

One week ago I got a new job at Walmart. The day I got the job (which was the same day) I told my manager that I would be starting at Walmart. I said I would get a schedule from them and if she wants to try and still have me do a closing shift here I would. She said she was probably just going to hire someone else. I have orientation tomorrow at Walmart, thank goodness I'm not scheduled to work here tomorrow. I told my manager that my first day there is tomorrow and said they are desperate in the department they want me in so they will be training me in there right away. I said so I probably can't continue to work here at all. I told her a week ago they will have me as an opener. She said I HAVE to give her 2 weeks notice and work the next 2 weeks here. I told her 1 week ago already that I would be leaving unless she wanted to work with me on my schedule. Please tell me what I can do because I need the job at Walmart and if I can't be there when they need I may lose my job there. I need advice please. This place has always fucked me over. I have done and done for them and my manager has treated me like shit. I feel like I'm being fucked over again.

*** I live in Utah!