I know you must be stunned - I think I can understand a little bit what you're going through. A couple months back I learned that I have a cancer that, according to my doctors, will most likely not be cured. They've already said that it may very well kill me one day, but that they are trying to do what they can to keep that from happening anytime soon.
Just some stuff to think about:
-Follow to the letter what your docs say, but question them every step of the way.
-Get a small notebook and make a journal with every ache, pain, pill, shortness of breath, etc, and bring that with you to your cardio appointments.
-Be sure to write down the time and what you were doing at the time when you experience discomfort, as well as any questions you thought of since your previous appointment. It helped me feel confident that my docs had all of the information they'd need to offer me the highest level of care possible.
-As scary as it is, remember to maintain a positive attitude - you and the people who love you deserve no less.
-If you don't already, consider doing something to feed your spiritual needs. Be it church, temple, meditation, affirmations, or whatever works for you, do something to cleanse your soul and lift your spirit. It really has helped me and hopefully it would benefit you too.
I know you've been knocked on your arse with this news. Feel free to PM me if you ever need to think out loud.
Take care brother,
-Chris.