I like a couple of phrases from SU's Hard to Say set. I use this set a lot with my friends who are battling cancer and other diseases..."I've never known someone so brave. I'm praying for you." and "You are stronger than this. You are brave and courageous. And let's face it, You're my friend so that means you can put up with anything!" and finally, "Life doesn't always happen just as we planned, but I plan to be there for you always."
Or maybe this ;
Please know that I am here for you.