Help my boyfriends an alcoholic

Iv been dateing my boyfriend for 2 years. Hes an alcoholic at first it was everyday. Then every week. Hes cut down a lot l. But hes a very bad drunk he goes though hundreds of dollars, drinks and drives, Iv found him passed out in his car or even on sidewalks outside of bars. Sometime hel go on a bender for days. He cant drink just one. And he cant stop even when hes reach the point of drunk. He will continue until he passes out. If he doesnt even drink that first one in the first place everything between us is perfect. Iv had it though. And finally made him promise no more drinking. Hes promised and broken it more times than I can count at this point. Because of the amount of times hes broken that trust. Iv become worried and paranoid constantly. When Im at work I think hes drinking at home... if I come home and his eyes are red I think hes been drinking and hiding it again. Today he went to work with his dad and sat in his dads garage nearly 2 hours. And I flipped out on him for not coming straight home because I think hes drinking in the garage in there like he and his dad always do. I dont know what to do. The trust is so broken Im constantly freaking out on him or worried stressed and paranoid.