He lied and broke a promise.

My boyfriend stopped drinking when we started our relationship 3 years ago. He went to a friends birthday party last night and told me that he wouldn't drink or do anything stupid. I found out he was drinking when I called him. he was completely drunk. Slurring words, couldn't speak right, and throwing up. He told me he only had 1 drink, but his friends said he had a bunch of shots, played flip cup and had vodka, tequila, and Heineken mixed together. This is the second time he's broken a promise and lied to me.