Hi There,
I'm sure you are currently freaked out at the prospect of having a heart attack because since your father in law had one and died from it makes it not just a passing thought anymore but a reality, especially for someone that was only 45. But just like everything else we "what if" or over analyze, you can be almost certain that your chances of having a heart attack are no higher than they were a few weeks ago. I'm not trying to preach as I too have a lot of anxiety concerning heart attacks, cancer, etc. I just try to reassure myself that if our higher power thinks it's time for us to go, it's time for us to go. I know that anxiety over long periods (30 plus years for me) is definately hard on the heart, but I try to stay in the present and remind myself that I am doing all that I can to keep myself from having a heart attack or any other disease and I just have to put the rest in "his" hands. Remind yourself that the more stress you put on yourself, the higher your chances of actually having a heart attack in the future will be. Maybe that can be a "positive" thought for you while you are anxious and help you to calm down quicker and easier (I know that's easier said than done, but it's worth a try

I hope something I may have said will help you out a little ~ I know that when I allow others into my anxiety, it seems to help quite a bit. Keep your chin up and just keep using your relaxation CD.