Well, a friendly way to do this, and that they probably should agree, if reasonable, is to buy / rent your technology. Thus, you can get a good amount for your work ( since you mentioned the purpose of this site, it was to make extra money in your question ).
Otherwise (if this is a pet project in the first place), you can also tell them in a friendly manner that you keep this site as a hobby, and you prefer not to share it, if everything is in order, unless they let you work full time on your own and reduce earnings, etc. (something that most people would like to do, work on their favorite projects and get a stable salary for it).
As always, first try to reason with the other side in a civilized and friendly matter, this is likely to make both sides happier, and it will be better than the legal route most of the time.
Robert Gould
source share