I couldn't make my exH do ANYthing. Drink included.
You did not cause him to buy alcohol, to put it in his mouth. It doesn't even sound like you did anything but break contact.
Every addict searches for any reason to drink when they really want to/need to.
He doesn't take responsibility for $hit.
My ex would drink because it rained that day, or because a 'friend' was sad.
Any reason. all reasons.
Please just carry on. Don't pick up the ball. Leave it in his court. It is HIS addiction.
Your addiction may be dealing with him. Just keep working on yours.