this happens to alot of cats. if the nail has not grown into the pads of her feet then you need to cut it. if it has already grown into her pad then take her to the vet. sometimes when the nail has grown into the pads and you cut it the pad could be already infected and can be bloody. if it is infected then the vet can give her an antibiotic injection and possibly wrap the foot up til it heals. monitoring the cats nail growth and cutting them every 4-6 weeks can help this from not happening again.
Most definitely take her to the vet to cut the nail, and make sure that it hasn't grown into the skin. The advice you were give is right on. If you can't cut the nails yourself, your vet will do. We do it at our clinic for $5. People think this is great, because its done and over and no stress to the pet. I think its the owner who the pet doesn't want doing this and they will test and get squirrely, but for someone they don't really know, they usually are pretty calm.