I'm not sure if I am getting your message correctly, but it sounds like you are trying to "fix" things. You said you "feel" like there is something you need to say to make her feel better. Just be honest. Tell her you don't know. Medical answers are cold when you are looking at someone you love struggling for answers, and not hearing what you want to hear. We want, "It's alll going to be okay, and here is how it will be fixed."
My husband passed yesterday. The night before, no matter how hard I tried, I couldn't make him comfortable. I stood in front of him in desperate frustration. He asked what was wrong. I just sat next to him and told him, "No matter what i do, I can't make you feel better." And I just held him. Words are not always needed.~~ If she says, "You have no idea what I'm going through,"... tell her no, you don't. Let her know your frustrations of not being able to help.Not being there in the night time is the worst time to be alone. I can't even imagine it with children.
This may sound lame, but, maybe leave her little love notes where you know she will find them. In the kids pajamas drawer. The fridge. Freezer. Medicine cabinet. Inside the phone reciever. You may not be there withthe answers, but you are there. It's all you can do right now. .....I guess.
You don't know what to do. She does not have the cure or answers no more than you do. Being frightened and helpless is the lonliest feeling in the world. The frustration and anger is beyond words, for both of you. She trusts no one. You don't know what she is going through, but, at the same time, she truly does not know what her Dad is facing each day. You are looking for answers for you, YOU don't give her what she wants.What about her Dad? Medically or emotionally, she is not hearing what she wants. It's not about her, but you want it make it better for her (understandably) and she's not making easy. (None of us do.) But, eventually, we figure something out. Research stuff, tell her "I read this" or I heard this, ~~don't try to answer questions you don't have a solution for.
Don't sell yourself short thinking your marriage will end because of it. My husband was the one battling cancer. More than once I made it known how frustrated I was,(indirectly by just being "cranky"), ashamed to say I made him cry once - ONCE. The helplessness, guilt and anger I felt ......is beyond words. But, once I took a breath, all I had to do was remember and think,(more than once) "I know I how I feel, I cannot even imagine the fear and challenges he has to face with courage each day, the treatments, the doctors appointments,what is this scan going to say to him - WHAT ELSE MUST HE ENDURE TO GET THROUGH ANOTHER DAY."
Not having really any idea of your situation, but it seems you are her only sounding board. It took me a long time to let go and finally really let him know how scared I was and felt like no matter what I did, it was never enough. It was the best thing i ever did. Let her know your fears as well. It may end up in huge fight (not in front of the kids) but, maybe some things can be said that you are afraid to say, need to say, but she may need to hear.
I watched my husband fight a battle very few would have endured. It still has not sunk in, so forgive me for using you as therapy. What I know is, no matter how many, or how few people we have in our lives - it cannot be done solo. And some will suffer the "wrath" when someone we love has to entrust thier life to strangers who only know the disease and not the person. I WAS THE ONLY ONE WHO KNEW BEST. (Sometimes, not so much.) I'm high strung - one of his docs used the word "tenacious" - nice way of saying bi****. But, we made it. No Regrets.
Remember, night time sucks. don't feel guilty. It will work as long as it's done as team. Even if sometimes it doesn't feel like it. Don't pat yourself on the back. Just back up when you have to. Crying is ok too. (Course, I'm a girl......hang in there.)
Not sure how much this made sense to your situation, but thanks.