You should notify your home-owners insurance policy and speak to your divorce attorney if you have one. If not, consult with a personal injury defense attorney.
I am very sorry to hear about this.... a divorce is hard enough on its own without this type of allegation. These are very difficult claims to pursue. It essentially requires a showing that you were aware you have the condition and concealed it. Especially with this condition, it is often difficult to determine when and where a person may have been exposed. I agree that your divorce attorney is a good place to start to get some assistance with this. You can tender this lawsuit to your homeowner's carrier, however, many carriers are now specifically excluding sexually transmitted diseases as a claim or "loss" they will cover. If your insurance carrier accepts the claim, they will provide you with legal counsel to defend this claim. If both of those options fail, contact a personal injury defense attorney, or an attorney who does insurance defense work. Good luck to you!