I'm so very sorry to hear that your mom is so close to ending this life of hers. Do you really think she'd freak out? I think people who are dying usually know it. I think she is putting on a good face (literally) for you...

Please consider talking with her about "what if" she were to die? I have found that the majority of people WANT someone to mention it and allow them to talk. It takes a huge burden of stress off them, and it opens the way to say all the things you need to say to each other. You need to talk about it with her, don't you?

I KNOW it is very difficult. Do your best, and that will be fine.