i have no background, but i suspect you could try to flip it to your advantage. that is, see what they're doing better than you, and copy it. another option i

i have no background, but i suspect you could try to flip it to your advantage. that is, see what they're doing better than you, and copy it. another option is to ping them and offer a deal - you let them sell it and take a cut, all legal. another option is keep selling your version and they sell theirs and just try to concentrate on building up your brand - which maybe the real purpose of selling an e-book/etc. - so that you can build your email list, etc. just some ideas. must suck.