Hello momto2boys: I don't know if your son remembers expressing the negative feelings he expressed. I don't know why he would not. Does he feel that way now? Probably. No, it has been my experience that negative thoughts & feelings don't go away simply because one starts taking an antidepressant.
If an antidepressant is working for a person, it may lift the person's mood in general & make it easier for him to cope day-to-day. But it doesn't wipe the slate clean, so to speak. Also... not every antidepressant works for everyone. It can take some time to find the best one for a given person. And you have to give the medication time to take effect... perhaps two or three months, here again depending on the individual. Also, after one has been on a particular antidepressant for a while (here again... it varies from person to person) the antidepressant can lose its effectiveness. Then either the dosage needs to be increased, another psych med must be added, or the person must be switched to a new antidepressant altogether. Everyone reacts differently to all of these elements. So there's no way to tell for sure what your son's experience will be.
By the way... it may also be worthwhile for your son to see a therapist if he does not already have one. Most people in the mental health field today, I think, feel that antidepressants alone are often not sufficient. But, here again, it's an individual thing. There's no hard-&-fast rule. I wish your son, & you, well...