I have heart disease, had a heart attack. I became very depressed in the weeks that followed and therapy was the treatment I added (already had prozac). It's been a huge help in identifying stressors, managing stress, managing boundaries (learning to say NO), being mindful about my choices, paying attention to the messages from my body, etc.
It is also hard when "you don't look sick!" to others; that's why it is great to have an online community (mine is WomenHeart) where everyone understands when you need to vent and cry and whine and say "Why me? Why more?"

Hugs and strength to you as you face the challenges!