The sadness is normal and quite healthy, but PLEASE don't blame yourself or your situation for your mother's death. NO GUILT!!! She was EXACTLY where she wanted to be ... where she NEEDED to be! You would do the very same thing for your son, as I -- and the other mothers here -- would do the same for our children! No matter what.
You are right; you can't give up now! She is still with you, sweetheart, but now she is even stronger. Her spirit is stronger than her poor body was. Let her help you even more now!
I am in tears and feel sick about this. If you need someone to talk to, please E-mail me directly and I will give you my phone number. I can hardly write this, as I feel your pain. I am sure any one of us would be willing to talk to you. You will be in my prayers tonight.