You do nothing about gossip because you can't change other people. People will say what they want and have that right. I would just avoid doing anything to feed into it. When they get bored they will move onto someone else. As far as the indiscretion you can forgive yourself anytime you want by focusing on your relationship and your upcoming baby. if you focus on the past that will take away your focus. Try to plan for your baby so that it is a time of positivity. Also focus on working on your relationship. Explore why you did this so that you have a better understanding. If you think counseling would help then access that to. If your husband knows then explore this together. You have to stop trying to fix what is done. You have the ability to forgive yourself by just focusing on your relationship and your child.
If this is helpful press accept