Knowing death is coming.

How do you deal with knowing someone you love and are extremely close with is close to the end of their life? My pap was diagnosed with stage 4 lung cancer 2 weeks ago. A month ago, he was fine and nobody would have knew anything was wrong with him! The past two weeks, he has went so downhill that I can't believe it. He is supposed to get radiation and start chemo soon. I have 45 days until my due date, I pray he gets to meet this baby. My dad died 5 months ago unexpectedly. This heartbreak is horrible. I feel like I didn't get to enjoy my pregnancy at all and this will be my last pregnancy most likely. Part of me feels like it's nice to know and be able to prepare but I can't handle him being so sick. It breaks my heart. When he sits there and can't catch his breath, I want to burst into tears. He's such a good man. I also have a 4 year old and she obviously doesn't understand that anything is going on. I can't imagine how to even explain to her when he does pass away. She loves him so much and we see them daily. Sorry, just needed to vent!! I can't sleep.