I'm a high functioning alcoholic and I want to quit but I'm scared of my family finding out.
How would your your family react to you being an alcoholic?
They're going to pester me for not being strong.
It's good that you want to stop drinking. You can keep your plans to yourself if your family isn't going to be supportive. If they are likely to hassle you about it, it might impact your recovery.
I don't care if they are disappointed, I just don't want to be like this anymore.
Overcoming alcoholism is a difficult journey, and one that should be a priority to you.  I'm glad that you are willing to put in the work necessary, and if your family are likely to be a hindrance, you can keep it to yourself.  Once you have made progress, you can let them know.