I struggle with this too on a lesser level: I still enjoy Harry Potter, R.Kelly's "I believe I can fly", and Michael Jackson. They're all works from horrible people, but the works themselves I find amazing and won't deny that the works better humanity by existing instead of not existing.
At the same time, with the exception of the works of HP, I haven't paid a cent on any of these works, so I don't feel like I'm directly supporting pedophiles with my wallet, so I feel like I'm in a position where I can objectively enjoy these works without it being spoiled by the morality of purchasing it
TL;DR - The deed is done and you yourself didn't buy it, so I think you could try the product with a guilt-free conscience and see if it's good. The only harm I can see you doing is recommending the product to other people who might buy it