Job or stay at home??

Yesterday something happened which is forcing me to re-think my intentions:

Grandparents were trying to play with S while he was trying to get to me. I was trying to Work from home and catch up on some work this weekend. Grandpa asked S to imagine that he would be in the same boat, working when he grows up since every adult has to work and so he should also let mommy work now.
" What would happen 15-20 years from now? " - grandpa.
" Mommy and daddy will go back to India and I will have to live alone here" - S, turning away his face with tears in his eyes!
"Why??! " - grandpa.
" Because that's what happens when you grow up! Parents have to go back to India. Don't you also go back to India and daddy stays here? I don't want to stay alone! " - S, still emotionally!
Grandma had tears in her eyes when she was telling us about this incident.

I am amazed at the grasp, understanding and the reasoning that S is showing at 5 years of age. Why, to me he's still a baby! I never thought he would interpret and generalize things that we take for granted! What else would he be generalizing? Would he be getting hurt that he can't spend more time with his parents? Would my career be hurting his feelings? Is my career even worth it? I don't even feel that much passion in my career anyways. When I am in office, I think about S, his cavities, his food, other things. When I am home, I think about hours lost in my distractions at office. I am effectively not doing any of these right. I have good intentions, but my approach is wrong. He probably needs me more than I need my job and its financial confidence. May be staying at home is the best thing SAH moms do! May be they are more privileged than working moms, in a way. They can really shape and mould their kids the way mothers should.

How can I get over this guilt that has made a comfortable place in my mind? All the world's richness and greatness would be nothing to me if my kid is not happy. I need to earn to make a comfortable life for him and for my own sanity. I also want to get more involved in his life, his daily activities, his feelings, more than just making healthy food for him. How can I do both right?? I can never be PV, the super-mom I know (she's amazing!). I can only be better than what I am now. But even then, just how??