Feeling like I've burnt out already

My mum has been diagnosed with breast cancer, it's been 6 weeks since the confirmed diagnosis and we've already been through 1 cycle of chemo, another 6-9 months of it to go. I live 15-20mins away from mum whereas my brother and dad both live with mum. 

I'm struggling deeply, my brother and dad are doing the best they can but I'm feeling the brunt of the workload. I work full time, I am at mums every day if I'm not working and I'm cooking, cleaning, dealing with her emails, making sure she is hydrated etc. I'm talking to her about other random things, trying to keep her mentally happy as she can be. 

My brother and dad who live with mum are, well a little bit lazy. I had mum call me over the weekend crying that she was lonely and her body was aching and she hadn't had anything to eat yet, she was worried that if the side effects get worse and I'm not at the house yet there wont be anyone to look out for her properly (I was in the midst of my night shifts at work and I couldnt help that morning). 

I'm feeling very lonely, I'm feeling tired, im feeling sad... I can't express how I'm feeling to mum. I've expressed it to my dad and to be fair he doesn't seem to care. He's avoided being there when the chemo sessions are booked, instead he's told me I'm strong and he still needs to be at work... he's a teacher... I dont understand how he cannot plan the days he needs to be off to be with mum whilst shes having chemo with management. 

To be fair I think this post is just about venting, there's not much I can do about the situation but it helps to Express it somewhere...