My friend who had these accusations chose to move away and distance from most people. The woman making the accusations was not in any way attractive or likely for him to have been tempted by. His wife is beautiful and lovely, so it seemed very unlikely he would have strayed.
Trouble with moving is, if you are the one to go there will be gossip saying it was your fault. Also, that's your home. You might not be as happy somewhere else. It might be best to brave it out and be honest with everyone who knows you. Those who know you will know your husband will know his best intentions, that he's a helpful man- and I'm sure the mud won't stick. The court case will also go into the neighbour's background, I'm sure.
Another thing that might have happened is that after all the kindnesses over the years, she may have grown close to your husband and made a move on him which he rebuffed, causing her a painful rejection and accusations to try and hurt him. You need to ask him and find a great solicitor.