Literally fuck my job 😡🤬🖕🏻

A few day’s ago my big boss called me into her office and told me (all employees as well) that there are big changes being made at my work. With these changes she also made me aware that there is a chance, I may never get full time here. That’s one of the reasons I quit my last job to come here. I loved my last job, but this one paid more hourly, and was offering full time. So then a day or 2 ago, my old job called and asked me to please come back to work for them. I was like “perfect, I’ll just work 2 part time jobs instead”. I went back to talk to my big boss about it today, and she was a complete witch about it. She said she refuses to help me get set hours, and she said if I take this other part time job that if I only start getting like 2 days here that’s it, she won’t do anything about it to fix it. I told her I would make this job priority, all I was asking was if there was a way to have certain shift so that I could do both jobs. She gives my other coworkers set hours. Like my 1 coworker that’s going to college has a set schedule. So does our closing lady and our opener. Like are we serious?! You hire me telling me I’ll most likely get full time very quickly, and then tell me I most likely will never get full time here and then make it pretty much impossible to have a second job for money that I need?! This is straight up bullshit!!!!