My mother passed away from Lung cancer last year. It was kind of sudden for us though. She had quit smoking as part of her New Year's resolution (along with my aunt and Dad (although he goes and sneaks a smoke now-and-then.)
Once she stopped smoking, I think she realized that she had this weird problem breathing so she goes to see the doctor. The doctor tries an X-Ray and doesn't spot anything. He thinks she might have asthma so she goes on all of these different breathers and medication but nothing works.
Eventually she goes for a second X-Ray and there's this tiny speck that shows up. So she goes on this waiting list to see a specialist (about a month long wait list). She gets another XRay done with the specialist and the speck is bigger. He tries to talk her into having a bronchoscopy done as they can diagnose it much faster then having her wait for an MRI.
My mother, as stubborn as always, says no, she wants to wait for an MRI. So, it takes about a month for the MRI to occur, and during that time she's freaking. And we're all trying to console her, it's nothing don't worry about it.
She gets the MRI done, and it takes another 2 to 3 weeks for the results and she goes to see her doctor who tells her that its lung cancer. Everyone tries to console her again, don't worry too much about it, it can be easily treated now a days, you'll be fine, you'll have a hard 6 months but after that, you'll get back to normal again. She starts to freak out more, the doctor gives her some anti-depressants and various other medication to try and calm her down, but she ends up being a zombie. She won't eat, she won't get out of bed.
So she waits another couple of weeks to talk to the specialist. By the time she sees the specialist, he flat out tells her: It's in both lungs, it's very aggressive, with treatment we might slow it down. He gives her about 6 months at most.
Within 2 weeks (before even analyzing the type of cancer to determine treatment), she suffers from pneumonia and lands in hospital. On the way to the hospital she had a heart attack because of the added strain of her heart beating too fast (her lungs were filled with fluid). My niece was taking care of my mother that day (my dad had to work, my live-in aunt has a home-based daycare in the basement of the house). As my mother was passing out, she said that she saw Lynne [one of my sisters passed away from Meningitis several years ago.]).
They managed to stabilize her and started to drain the fluids from her lungs. She spends three days in ICU (never once gaining consciousness). We make sure that family is always with her when possible (my girlfriend and I spent a few nights at my parent's house with my dad and a live-in aunt). It's a hard time as my sister was in the middle of a move, my niece was in the middle of her move. Several other crisis happened and one day my sister just couldn't get out of bed. [When Lynne passed away, my sister was the strong one, she helped with the arrangements, she was the shoulder to cry on... This time she couldn't bear that responsibility.] That day things were actually looking up, my mother was back to almost breathing fully on her own (the machine was more or less doing the timing.)
The last day, she's back on the machine, the doctors couldn't analyze the cancer from the fluids. They ask us should we treat her as a cancer patient or as a terminally ill patient? They reiterate that she won't be cured, she might have a "week" back home at most if she survives treatment and it will be very hard. Our answer doesn't matter as that same night (around 2am), we get a call from the hospital to make our way there. Once we got there, we were told she had a second heart-attack and they can't get her blood pressure high-enough. We all say our good-byes, the priest gives the last rights. We're escorted out of the room and called in once the nurses finished unhooking her from the machines. We go in for our last goodbyes and head home.
How did I live through it?
For one thing, the nurses at the ICU were absolutely stellar. They not only took care of the patients, but they took care of their family as well. They would talk to my mother and encourage us to do the same. They would take the time to explain what was happening to my mother and the people present.
I also think that it was very helpful to be able to see her during the last few days. To be able to interact, at least in a way, with her.
I can't say that you'll get over the pain... Once and a while, it comes back. But you just and have to try and remember the good times and stick remember the people that you still have.
For me, it mostly hits me when I'm planing for the future... She won't be around to see the new renovations, I won't be able to give her any souvenir from my up-coming trip, she won't hear of my engagement, she won't be at my wedding... Although I guess our family has this penchant to think that in some way "in spirit" she will be present. And, umm, I'd avoid watching "About Schmidt..." as well... I rented it on a whim and the beginning kind of hit me hard...
I don't know if this helped in anyway. But just make sure that you spend some of the time you have left with her. If she can't talk to you, then you talk to her. Tell her some of your memories. Keep an eye on your father and any other siblings you might have. Oh... and vent when you can! [umm... preferably not to relatives...]