My girlfriend is too sexually needy when she's drunk so I want to cut her off
Why would you want to cut her off because of her sexual neediness?
Because there is too much pressure for me
You should be more communicative with your partner. You are not expressing how you feel well enough so you should talk to her or she will end up breaking up with you due to your lack of communication.
It's easier to just be mean to her and cut her off.
I don't think it's right for you to be mean and cut her off because that isn't going to solve anything. If you're honest with her then maybe she can work on her behavior, which will lead to both of you being happier.