You may be fed-up, but that doesn't give you the right to slip medication to your boyfriend, especially when you know there are potential serious side effects. Please, do the right thing and call a medical profressional and tell them what you've done.
You can find plenty of support for yourself on this site. It's important for you to understand that you can't control what and now much your boyfriend drinks. Make that phone call, and then feel free to join us on Al-Anon to learn how you can free yourself from your obsession of trying to control his addiction to alcohol.