What can I do?

Hey so I feel like I shouldn't really be talking about my family problems on the internet like this but I need some advice.

Let's just say it's a long story between my mom and dad, my dad has cheated on her many times during their marriage and even when I was born, my dad does have a few problems with alcohol. It's not a few but his a alcoholic, it's ruined the relationship between my mom and him. His always out going to clubs and bars with his friends and it got so bad that he was fired from his job, he has a new job now.

Me and my mom tried getting him help with his drug and alcohol addiction but nothing worked so my mom is just tired of him. She said she doesn't care about him but I always hear her crying about him to her sister or mom on the phone.

His tried stopping, but it only lasted 2 months before he started to get drunk again. My relationship with him has never been good but I'm at a point where I'm concerned for him.

What can I do to help him stop? I'm not sure where to post this but I hope someone could help or give me advice.