I don't know how to get through this

My mum had been terminal for over a year, she had a chest infection and was admitted to hospital. We spoke to the doctor yesterday and it was positive news the infection had gone right down and they were looking for her to come home. I only stayed with her for an hour in the morning as she had been delirious as part of the infection and it was really upsetting for my daughter who is only 11. I was just getting ready to go late afternoon, I'd spoken to her on the phone less then an hour before and get a call from the doctor to say she had passed away suddenly. I promised her I wouldn't let her die in hospital and I promised her I would be with her all the way, I feel so guilty that I couldn't even do what she wanted at the end and she was without me. I don't have any other family my dad passed away 19 years ago and just feel so alone, she was my mum, my best friend and my rock. I'm 6 months pregnant and have my daughter to think about otherwise I really wouldn't be here, I just want to be with my mum.