Staying strong but breaking inside

I don’t do this sort of thing normally but found myself googling one night “my dad is dying of cancer” when alone, as I do these day when trying to come to terms with reality but also my own feeling of sadness, anger and loss. My dad is 61 and already spent 2 years recovering from 2 major bowel cancer operations to finally diagnosed terminal. I am a very strong woman and I continue to stay strong for my dad and front for everyone else who I know worries but I am completely breaking inside. The injustice of it, the fear of the pain that he may yet to go through and the dignity that I know he holds dear. I honestly can’t imagine a time when he will not be in my life and the guilt of feeling that I am mourning him already. I know there is no answer to this and that there are thousands of people who feel this pain, but I feel so alone. Thank you for giving me somewhere where I can just write this down