Batteries dead

It's raining and i just got off work. I got home and the dogs were begging me to take them out. So I decided to take the car. I haven't drove this car for awhile (I love my avalanche) neither turnning it on. When I let the dogs out, I forgot to turn the headlights off but it was less than 5 minutes when I noticed it but here I am, car won't start..