You are back and ready to try again-- that is the important thing. Don't worry about the slip up that you had- most people have those a some point in their recovery. Just remember that right now is the most important time and keep going forward. Yesterday is in the past. You are getting a new chance here. Keep any kind of booze out of your place so you won't be tempted. Don't buy any new bottles to have around.
You can do this. talk to your cousin and just be honest. Secrets keep us sick is the phrase that I heard. So just open up and let your cousin know what happened.
Stick with it and keep on going forward.