phaeton wrote:

....
...We're going to pull an attorney out of the yellow pages first
part of next week and run all this by him/her to see where we stand
under the circumstances and within the laws of our county/state.
....

As you're now realizing, should have done that before...

You have no obligation beyond a written offer, but if they have accepted
an offer, they can most likely enforce it if they choose to do so...but,
definitely get legal opinion but since you've already made a move it may
well be too late for anything except minimizing further damage.