Can't pay me back but can buy Ciggerates and McDonald's?

Me and my boyfriend live together at my moms place. We both pay $50 a fortnight to my mom to help with bills, groceries etc. With his credit card he can't transfer money to anyone so he usually withdraws cash and gives it to my mom but because of covid-19 cash payments are not allowed so he asked me to transfer $50 to my mom and I can use his card to spend $50. I order some stuff online for $20 then a few days later my mom asks me to buy milk I say I'm broke I'll get money off my boyfriend. I ask him to buy milk. "I only have $20 left I need to pay my cars registration" then he goes and buys Ciggerates, McDonald's then a bag of chips and says it's ok I just won't drive my car till next week. He doesn't see why I'm mad. I would of let it go if he had just brought milk. Am I in the wrong got being mad?