Drinking too much soda and staying home sick from school

We normally do not have soda in the house, but we are having some friends over this weekend so I got some Pepsi for mixed drinks. Last night, my 15 year old asked if he could have a little, and he was allowed a juice glass of it (~6oz)This morning, he asks to stay home from school because his stomach hurt, and after discussing that he'd be missing school for something that would probably clear up in a couple hours, we let him stay home. This is the first day he's missed all year and he's got straight As. If he came to me for a mental health day, I'd give it to him as well.Tidying up before work (I work from home) I found that he had actually gone back and drank all the soda, approximately 30 oz.I need to log into work, but I'm so mad, mostly at myself. I overestimated his ability for self control and left him to do something that legitimately has made him sick.I've taken the TV remote and when he wakes up I'm taking his phone. There's a number of low impact chores he can do around the house. I just can't see allowing him a chill day off school for this. I could take him to school late, but it would be tough for me to miss work.He'll get his phone back at the time he'd normally get home from school, and once he's done with chores he can get his missed assignments from online.I don't know if I'm looking for advice or support or criticism or what. I'm just at a loss via /r/Parenting https://ift.tt/2Gm3ada