A little extreme perhaps, but normal I think. You just "lost" your son. He's not going to come home to live anymore, doesn't "need" you anymore, you have to go back to your normally scheduled programming and live only for you. That can be very difficult.

I just retired a couple of years ago and I'm still having a lot of trouble getting used to not working. We get into a rhythm and pattern of who we see, what we do, how things "will be" and when that changes dramatically with births, deaths, graduations, marriages, retirement or other major life events, that's stressful!