My lovely best mate was a functional alcoholic, until he wasn't. Early 40s. He could go periods of time without drinking, until he couldn't. He didn't drink till the evening, then the afternoon.
The day it really hit home with him was going to the GP for a different reason, so he thought, but his symptoms were withdrawal. From that day on he was advised to drink a level of alcohol a day to prevent seizures and the other horrible things that come with withdrawal.
He had to surrender his driving licence. He moved on from beer to vodka. Currently on a litre bottle or more a day. He has lesions on his liver and nerve damage to his feet, back and eyes.
Thankfully, he's accepted his dependence and will be going into detox very soon, then up to 6 months of residential rehab. I've supported him through this and only because he has been willing to fully engage. I'm really excited for him to have a sober life. He'll never regain his health fully though.
This is what you could potentially be facing. You can't have this around your twelve year old, you just can't.
Until your dp is willing to accept his dependence, nothing will change for the better.