I read the Op and probably about half of this, so may ahve missed some answers.
I dont know if the thread is a joke or not, but can understand some people could have this problem or even simply just have a flirtatious friend which annoys them, so am going to answer as if it is real.
Swingers does not mean 'We are going to gang up on you with your husband and make you fuck us' it means 'we are a couple who enjoy consenting sex with other adults'. So I wouldnt be so sure that they would want to swing with you anyway, FWIW, If they often mention swinging to you and havent asked you, it's unlikely they want to.
Doing something sexually which is consenting, no matter how you feel about it, is not disgusting merely not to your taste.
Have you and your DP never discussed fantasies?? I knwo that DP would be horrified at the thought of swinging, there are things I and he would not try but have place in fantasyland that we have discussed, so surely you should know your husbands fantasies?
If you do like this couple, then tell them the sex talk offends you and could they not get into it when you meet, you can also tell the lady that you dont appreciate her asking DH to 'cop a feel', though it seems to me she is joking rather than deadly serious.
Sexual attraction is sexual attraction, doesnt matter who or how many you do it with, there has to be something there.
And for the person who said it was being unfaithful, I assume the couples dont see it the same way as there is no deciet, no pretence and no offence.