How do I know how much my B&B is worth, I have had the house
appraised, but what about the business IN half the house? Is there a
formula?

It would help to know where you're located. Business appraisals are
usually considerable more expensive than residential appraisals, as
mentioned in this article about innkeepers in Florida:

"Many are shocked to find that a business appraisal costs $5000-$7000
compared to a residential appraisal that costs $500-$700."

http://www.floridainnbroker.com/Index/publicationsR.html

Here are several sites that could be of interest to you:

http://innmarketing.com/articles/article15.htm
http://72.14.207.104/search?q=cache:ssBKdIjI8lcJ:www.yellowbrickroadnl.com/inside_ybr.htm+b%26b+appraisal+price&hl=en&ct=clnk&cd=5
  Only the cached site came up for me.  Here is the link: 
www.yellowbrickroadnl.com
http://www.bedandbreakfastforsale.com/index.cfm?fuseaction=openresource&resourcename=valuation
http://www.bbteam.com/Article131.html
  Look at the other articles.
http://www.innbroker.com/innkeeper.html
http://www.innmarketer.com/tips.htm

I do commercial appraisals in the Pacific Northwest and have been
involved in several B & B appraisals in the Glacier National Park
area.  None have involved a business component or a value exceeding
the value of the real estate.

The short answer is there would have to be some level of net operating
income after all expenses (including management, owners labors, etc) 
as well as a return to the real property.

Some interesting questions would be:

1)  What was the value of the real estate?

2)  What is a reasonable net operating income (specific to the
comments above) annually?

That might give you some insight into whether or not there is a business component.