To put this in proper perspective, if you had a choice of only stopping your sugar or smoking, I would strongly recommend stopping the sugar as in most people it will cause more damage than the smoking. However, you need not become obsessive about sugar. If it is the 4th or 5th ingredient in a food, that would probably be acceptable. However, many people are addicted to sugar and should avoid all sugars permanently for optimal health. This is not much different than someone who is addicted to alcohol and requires total abstinence.
Most people find that stopping sugar is very difficult.
Some people are very sensitive to this chemical and should avoid it. Most people will know if they are sensitive to it. It is wise to minimize your use of this product. There are more adverse reactions to Nutrasweet reported to the FDA than all other foods and additives combined. In certain individuals it can have devastating consequences, please try to avoid or severely limit its use.