I don't think they would, at least not from their close friends. He hated Neil, but he still loved Lynette. Also Miranda and Vivian would try (and certainly would) find out the truth, because they know she would never skip town without telling them and even if she would, she would at least get in contact again after arriving where she and Neil would want to go. Viv might look like an airhead in the few scenes we saw her in, but Miranda seems to be quite intelligent.
Also it's difficult to keep such a secret hidden from influential families over a large amount of time. If they want to, they have the means to find out the truth if the have the time for it.