Why did I think this was a good idea

I just started back to work after mat leave except I applied for a higher role in a different department whilst I was off so returned straight to the new area. I HATE IT. It's only been 1 month and I know I must stick it out but good god I hate it so far. I dread every day im there. It is ridiculously short staffed and I'm expected to do the work of 3 people. Most of the people are nice which is a positive but they are all so stressed and stretched that it's a horrible working environment. I'm a nursing sister if that makes it more clear, everywhere I've ever worked has been short staffed but this is beyond anything I thought was allowed to happen. I'm scared for the patients safety and everyday I'm scared I will make a mistake and something bad will happen. I wish I could just leave but I can't justify that decision. I miss my son so much when I'm there which im telling myself is probably making the transition harder but please tell me I'm not alone and others have felt like this and it's going to get better? I walk in and think I wish I was the cleaner because at least they don't have to deal with all this pressure.