Yes! You go mama! You and your youngest deserve this moment and so many, many more! 
My son said to me when we all went out to dinner, it’s nice not having to worry about her, his sister. At first I felt it too and was ashamed that I let intrusive thoughts in. But you know what? Our “helping” does indeed affect our other children and we must take in account their happiness as well, they deserve a wonderful moment and moments with their Mom being present and totally focused on what we are doing. I wish you a wonderful day tomorrow and heck, have 2 scoops of ice cream! 
Enjoy life.
