I didn't let you do anything!! You just took it and drank it!! It's not like I could have stopped it!!

[He knew saying it was going to make things go badly but he had to know and the only thing that would make Lan Wangji do such a bold thing would be alcohol so leaving that part out would have been a bigger mistake.]

When you want to do something, Lan Zhan, it's not exactly easy to stop you..

[There is no one who knows Lan wangji's drunken antics better then Wei Wuxian. But when the man simply picks up the cup and downs it before he can say anything..well..what is he to do?]

I knew I shouldn't have said anything..forget it..

[And so he still doesn't have an answer. His shoulders droop.]