Dan,
I was in a similar position you are in and also stayed in the hospital for two weeks. I have severe, drug resistant hypertension and related organ damage. Is your cardiac damage from hypertension? I am sorry you're going through all this.
You could be describing me last year. I could not make it up the stairs without stopping. I could not do anything. Felt sick all the time. I remember going into the garden to weed one day, sitting down to be more comfortable, only to find that moving my arm required too much of an effort and I could not handle it. I just sat there and cried and cried. It is moments like those that make us question whether our lives will ever be normal again.
Our bodies are very resilient. Internal mechanisms work very hard at restoration of all functions. Most existing damage can be lessened or completely reversed. Whenever that isn't possible, our bodies find a way to compensate. Basically, we just need time to heal. Do not give up hope. I never did though came very close to it many times. Things will get better. You have to help make them happen by remaining positive. Do what you can towards that goal - one little thing every day that you can feel good about.
I was able to return to work after a ten month absence late last year.
Your sleep apnea can be treated. Your blood pressure MUST be brought under control. The longer it stays out of control, the worse the consequences. I am sure you've been counselled about your diet and stress management, which are also very important. Anyway, I just wanted to say that things will get better in time. You'll lead a normal life again - well, slightly different normal than before. You are still getting used to your medication and its side effects. That's another reason you feel the way you do. That will also get better.
Best of luck,

flowergirl