I know I came off very emphatically! But the thing I should have also realized is that you do have YOUR intuition about her and the situation, and the fact that she went all out to help a friend raise funds for breast cancer does say something about her altruistic bent.
If she's not an actual neighbor, that WOULD be a bit better.
Here's what you should really do -- you should arrange for all of you to see a therapist who specializes in third party reproduction and speak together as well as separately and then go from there.
I am going to soften my earlier stance and say that if after the therapist sees everyone, you all still feel good about going forward, then it might be a good thing.
Good luck and keep us posted!!