I'm totally doxing myself with this, but I don't care. I don't know what to do, and I need your help, GT.

I took my dog to a specialist this morning because my vet found a growth near her heart and lungs, and thought I should have it checked out. Well, the news isn't good. She has a lung tumor, which the doctor told me is likely a cancerous tumor. Like, 90% chance. Even if it isn't malignant it needs to be removed. The only treatment is surgery. My girl is 13 years old, and I'm not sure she can handle this kind of surgery. I'm so upset, and I have no idea what to do. If I decide to go ahead with the surgery there is a chance she won't even make it through the procedure due to her age. If the procedure is successful she will live another 1 -3 years before developing another tumor. I'm terrified of going ahead with the surgery and diminishing her quality of life just to buy her another year, but I'm also terrified of not getting the surgery and watching her succumb to the lung cancer. I feel like she's screwed either way. This is the hardest decision I've ever had to make. She has gotten me through some incredibly difficult times in my life, and I know that sounds ridiculous. It's ridiculous, but I don't think I would have made it through the past two years without her. I feel like if I decide to forego the surgery I won't be able to look at her without thinking "I'm not doing anything to save you." But, if we do the surgery and she has a difficult recovery, or doesn't make it through the surgery at all, I won't be able to look at her and not think "I did this to you." This is the hardest decision I've ever had to make, and I have no idea what to do. I've been crying all day, and cuddling the shit out of my baby. This is hard. This is really fucking hard.