I lost my brother aged 17 to cancer 20 years ago, I know exactly how your feeling. He only had 7 weeks to live after he was diagnosed,but for two years we were in and out of a&e with him before they discovered it was nonhodgkins lymphoma. Because he was the baby of the house and originally there was 7 of us in it, we easily distracted ourselves from the reality,but none of us believed he would leave this world, one day he asked me to tickle his back and sit beside him, my selfish grief, made me leave the room as I knew i was gonna break down although he was strong for his 6 older siblings and parents through it all. I regret that to this day because after 20 years, I realised all he wanted was for me to be beside him, safety and comfort knowing, no matter what was happening, it made him feel good me being there. While he was suffering, I was whimpering and that's normal too, but if we know that ,there time is near, we need to, know matter how hard it is, just be there for them and make them feel safe, my prayers are with ye x