Am I overreacting?

Yesterday was our 2 year anniversary (marriage) and he left to go with his cousin for "one hour" but was gone for 5. He promised he wouldn't be long because we needed groceries. (Absolutely nothing here to eat or munch on) (and we share a car so I couldn't go myself and I have no family here to help) anyway he came back with some fast food, and later in the evening the cousin and his gf comes by and informs me that he was not doing what he said he was and that they were all on a "blunt ride." They thought I knew. I felt so stupid! He lied to me over something that small. And he knows my ex did that to me for years; just left me at home with nothing but he was out cheating not smoking. He keeps saying I don't have a reason to be sad because"its not like he was out cheating." Ok I still looked stupid in front of your cousin and was lied to. I do feel hurt and curious about other lies now. But he's making me feel like I don't have a reason to feel this way. I just want to be alone. I don't have anyone to vent to about this.