HELP - In need of advice

My bigbang is nearing the 11,000 word mark and I was about to begin to drop hints to what the alien menace was, except now I have a problem.  I just read the Torchwood book  Another Life, and while it's not exactly the alien storyline I was going for there are plenty of similarities.  I don't know what to do.  Should I:

1- Write it the way I planned and hope no one notices the similarities or accuses me of copying the book's premise?

2- Try to figure out a way to rewrite the alien menace to limit the similarities as much as possible?

3- Give up, since there is no way to alter the story to the point that there aren't some basic similarities or assumptions?