Help! I'm afraid of my own heartbeat!?

Ever since I started getting panic attacks, I've been terrified of feeling my heartbeat. I began getting attacks about 2-3 months ago. I can't do anything strenuous or physical that would raise my heartbeat cause the feeling is so similar to a panic attack that I'll just have a full blown panic attack that feels like it lasts for like 20 minutes. I'm afraid of getting a panic attack while my heart rate is already fast and dying of a heart attack or going into cardiac arrest. I've talked to a nurse and she said nothing bad can happen except I'll begin to hyperventilate, but it's hard to beleive that that's all that can happen when you get a panic attack ONTOP of an already accelerated heart rate. Even when I'm sitting down and I feel like my heart is beating too fast, I'll have a panic attack. So how can I get over this fear of my heart beating? Please don't tell me to straight up just work out, cause I can't that's the problem! Lol.... :(