Guy didn't die, he simply wanted to berate her family again, but talking made him calm down.
The coin with the butterfly and madame words strongly hint that he was or used the butterfly to make them find the ores, likely all said and done he couldn't bear to see her die after all that suffering, and later decided to curse her family, possibly the ancestor herself was never hexed by him.
Rhyme loved the ancestor, but not her family, possibly for having her husband blood.
Called it a game but there was no way to "play" it for the cursed ones, possibly meant as they were his plaything, stress relief.
So madame words are wrong, he did help the ancestor, immensely, is just that even up to her coming death she refused to ask for help by someone she turned down, could even be respect for Rhyme, didn't want to use his feelings towards her.