Well although it comes as absolutely no surprise, I'm glad for you nevertheless.
This represents the perfect juncture for you to realize that there is truly nothing wrong with your heart.
Do you best to be as open as possible with your therapist to gain a better understanding of the kind of thinking patterns that led you down such a difficult path so recently. Therein lies the actual difficulty and the answers you really need to reduce your anxiety and worry.
Finally, I'll tell you that a thallium diagnostic test can pick up even the slightest trace of a problem, so the fact that you received such a glowing report means your heart and cardiovascular system are in absolute perfect health with no chance whatsoever for any symptoms you may be experiencing to represent anything bad at all.
Again, I hope this marks a turning point for you. You'll be just fine, Kevin.
Best regards and Good Health