[soneill]

This is not legal advice.

Go here: http://www.probono.net/

Find your state and see if you can find a pro bono attorney or two. Give them a call. See if one can refer you to someone who does pro bono patent work. Gather whatever materials you can that prove your business was created prior to the filing of the patent, and have it ready to give to a lawyer. Do not reply to their lawyer again until you speak to a lawyer yourself.