Being sued in the High Court or county court for a civil claim is not a pleasurable experience. Of course, if the claim is groundless, it will be thrown out (perhaps soon after it was started) and the claimant who brought it will almost certainly be condemned to pay your costs. But those costs cannot reflect any damage to your reputation and health and some financial losses such as loss of earnings may not be covered.
Lament not. The Supreme Court ruled last week (by a majority of 5 to 4 of the appeal judges so close but a majority is good enough) that compensation can be sought where loss has been suffered by one individual because of a groundless claim against them by another individual. The victim's claim would be for malicious prosecution which was widely felt to be limited to groundless criminal cases only.
It won't be a walkover. You will have to prove that the claimant had no "reasonable or probable cause" and acted maliciously in suing. You won and the claimant lost? Not sufficient in itself. The claimant thought he would or might lose? Not sufficient in itself. However, if the claimant brought the proceedings knowing they were without foundation, you could well win. And so too if you can show that the claimant was indifferent whether the allegations they were making were supportable and brought the case in bad faith to secure some extraneous benefit to which they had no right (for example, to see you suffer as they had some grievance against you).
You might care when on the wrong side of a groundless claim to add this paragraph to your armoury when communicating with the claimant -
"You claim is groundless and I believe that it is not a bona fide use of the court's process. In these circumstances, I give you notice that unless proceedings against me are abandoned, I reserve my right to bring my own proceedings against you in due course for damages for injury to my reputation and/or health and for such other losses as I may suffer as result of the proceedings in the tort of malicious prosecution. I draw your attention to the judgments of the Supreme Court in Willers v Joyce and another  EWHC 1315."