My dear dad had a similar - worst type of his particular cancer that gave him less than a year from diagnosis.
I remember crying and hugging him telling him it felt like he was going to have to get on a bus and leave us, and that he didn’t want to get on it, and we didn’t want him to get on it, but there was bloody nothing any of us could do.
It’s heartbreaking. It’s horrendous. But you will do it. You don’t want to, but you will do each day as it comes. You will love, you will smile and laugh and there will be special moments despite the sheer agony of it all. This time will teach you about yourself (good bad and ugly) and you will grow from it.
I found gratitude more relevant and useful than hope. So grateful we had time to say all we wanted, that he had time to sort his affairs.
My dad had zero treatment options and went straight on to palliative care and pain management. The downward trajectory is really tough to deal with, but in a strange way I think we all felt that there was a small blessing to not be in/out of hospital door scans, then anxiety waiting for results, then hope of treatment working. I guess there were no “distractions” and we could all just focus on getting through each day/week….
And it really was a short term focus - I couldn’t think too far ahead, so kept a perspective that went no further than the end of the following week.
I highly recommend speaking to your local hospice, not only for end of life care, but also for pain management (better than the hospital or community palliative team in our experience), and emotional support…. and they will likely look after you as a family, not just your parent. The support we had from our hospice was honestly incredible, they made the unbearable a little bit more bearable.
Don’t let in more than you need to right now. Prioritize your family and keep your boundaries firm and only do what you feel is manageable, this is no time to be giving yourself over to anyone and everyone. If you can find some time, or a place to go to, on your own, where you are not daughter/sister/mum/wife, it’s good and important to carve out a tiny bit of space. It’s not selfish, it’s “recovery”, you will need time to just breathe.
You will do it for your parent. Honest, you will find a way. My heart goes out to you, knowing the journey you all have ahead of you.