Your epiphyllum plant is most often bothered by mealybugs and mites but from the image you sent it looks more like snails or slugs have found your succulent plant. Is the plant outdoors or in an area where snails could reach it? Check under the pot and near the stem of the plant for tiny slugs or snails that hide during the day. A slug bait such as "Worry Free" or "Sluggo" are both good effective at killing slugs and snails but not toxic to pets and wild life.  Don't worry the plant will make some fresh new growth and you can snip off the damaged leaves to improve the appearance. Keep growing, Marianne Binetti