Cutting People OUT because of Narc

Morning campers! (or indeed, afternoon, evening - wherever you are in the world). I have had a restless night wondering what to do regarding going NC with a friend who - purely by coincidence not design - has occasion to work and socialise with the Narc. This person has inadvertently become a huge and very unwanted trigger. So much so, that I am sure the only thing to do is to cut them out completely. Is this my problem? Am I being a bastard and putting the blame onto an innocent party? I know the sensible thing would be to explain the situation and why I feel this way to them, but even the idea of doing that sends shivers down my spine and I really really don't want to re-live the Narc hell again. Clearly, I've a LOT of work to do - so is it the best thing to do in the long run? I know it sounds selfish, but after all I've learned (still lot TO learn), it's all about ME now. No-one else - and any connection to Narcville is very dangerous. Would appreciate any comments. Flo x