Gerard, you share names with a fantastic Scottish actor many of us ladies swoon over, take great care of your wonderful self and you're going to be back on track very soon. Wrapping one's mind around a doctor getting inside of us and digging around is very very hard. I learned the phrase, "THIS TOO SHALL PASS," and, better yet, that this is my "NEW NORMAL." Ever ask a parent of a lovely little handicapped child how they do it? He or she will typically tell you, "This is just normal for us." That doesn't mean they have it easy, it just means the rules have been changed and they adapted. I lost a younger wonderful brother to suicide 13+ years ago, that poor kid (a medic firefighter, one of the best, age 26) just got so damned overwhelmed and distraught and I remember wondering how I was going to keep going without him. NEW NORMAL. THIS TOO SHALL PASS. Some of the lovely folks I met on a survivors board way back then and I are still very close friends.
Fear is the greatest enemy you've/we've got. Some part of you has to get downright ornery (we use that word in the south, it means stubborn, determined) about kicking this thing back where it belongs.
What you are experiencing is normal and makes so much sense. What can't happen is that you let it stop you from living and THRIVING. The miracle is that you found this before your heart enlarged anymore. After your surgery, I promise you that you will be able to return to your athletic way of life. I sure did.
Never give up. Keep looking for help on the medication for the panic attacks (I've only had one, all the tubes and wires recently in an ICU bed against my body suddenly were more than I could bear, my nurse gave me something that helped) and get going on that surgery and rejoin the living!! We're out here telling you that it can be done - you're no different than us except where you are along the road. Best of luck.