Thank you for the replies.
I don't think my son was permanently scared by my mood that day. Our home is relatively stable and he really didn't seem affected, other than mentioning it the next morning. It has made me realize that I need to be more accountable for my behavior though.
What I was really sad/shocked about was how easily he could assume it was about him. It was a good teaching moment though, I got to tell him that he can always ask me if he thinks I'm upset about something he said or did and I will tell him the truth.
That's another thing that drove me crazy in my family of origin, we were rarely directly told things, you always had to read between the lines.
This moment truly helped me put my own childhood in perspective. I'm in my late forties and can still remember hurtful things that my mother said to me when I was around 8 years old. Intellectually I have always told myself that it wasn't about me and I'm actually starting to believe it now.
One day at a time ....
db