How would you react??

My SO is a health freak and I eat very healthy as well  but every once in a while I enjoy a candy or so. So I went out a bought some trail mix with the m&ms (healthy and junk food!! Lol). I gave a little handful to our 14 month And my SO comes home and freaks out on me for giving him a couple M&ms in the mix I gave him. Starts yelling at me, calling me names and then tells me I don't care about our son and I am ruining his life. And then, takes MY bag of trail mix, opens it and dumps it in the garbage!!!!!!! Ummmm whatttt?! 😡
I don't think a little m&ms is going to hurt my son, plus that was the first time he's even had one! 
Anyway, I seriously wanted to slap him cuz that's totally unnecessary and going way overboard, but I kept my calm.
 I'll just buy another dang bag of trail mix! Lol
How would you react if your SO did this?