I don't think it was just burning the cards. I think it was your internal state. You could have burned them with a different feeling or no feeling at all. But your ritual matched your feelings of letting go and weirdly he felt it.
I can't explain stuff like this but I do see it happens.
I am just not ready to let go - I wish I could. I mean I could burn all the cards, but my heart wouldnt be in it. Takes time.