D.B.
Your question's title implies that the friend is the problem and is toxic.
By the end of your question, you seem to acknowledge that the problem is your husband: his lack of involvement in your family, and his excessive drinking. So that's good - you understand where you are at.
And I'm so sorry you are in this situation.
You say you won't divorce him because you have 3 kids. So here's another way to look at it: your 3 children are learning that it's acceptable to drink 12 beers a day while sitting around a pool (how dangerous is that?) and operate a grill and just feed a friend vs. the family. Unless your husband's friend stays over or calls a cab, they are learning that it's okay to drive after that much drinking. They are learning that a woman's needs don't matter at all, and that a "marriage" consists of 2 people occupying the same house but having such poor communication that one person checks out entirely (not wanting to be with his wife at all) and the other becomes a nag (whether that's your view, it's your husband's). And he has spent all your family money on beer, on golf and on renovations that your family can't enjoy because it's a Men's Bar & Grill.
This drinking problem has been ongoing for many years, and you have put up with it. Go to Al-Anon and get your kids into Al-A-Teen. Get individual counseling for yourself and the kids, even if your husband won't go. Don't keep trying to persuade him to do this. You are way beyond "date nights" and "family time." Your marriage is in severe crisis and you have to, for your sake and that of your children, get a handle on why you put up with this. You also need to see a financial counselor and get your affairs in order, because your husband is in a downward spiral - he is blowing your children's money, engaging in risky behaviors, and is not going to keep his job, let alone live very long, given this lifestyle and his decision-making. Work with a therapist and a planner to start to set the wheels in motion to separate your children from this nightmare of a role model. You are damaging them far more by raising them in this environment than you would by separating them from their father's destructive actions.
ETA: based on your addition that you are splitting up, I think you really REALLY need an advocate for yourself. If a mediator can represent both of you, it's cheaper. But still, you have absolutely got to get someone on your side here. Splitting assets down the middle? No way. You have 3 children, with college and orthodontia and school activity fees and who knows what else looming. You absolutely need to figure out a way that he is NOT driving those children anywhere, or having them around the house with a pool and a drunk father. You are going to have massive behavior problems with those kids - and who can blame them? You should consider a way to inform the law enforcement agency of his behavior so that they can drug/alcohol test him on the job. Yes, it puts his problem on their radar, but if he's involved with the public, that's a huge risk to a lot of people. Maybe they will force him into treatment. Get some really good legal advice on this. He needs life insurance (and a lot of it) and you need some assurance that the premiums are paid. If he loses his job and throws away the savings or disposable income on his partying ways, can you support the 3 kids? Is he keeping the house with the pool and the outdoor kitchen? Then can you afford to move and keep a roof over everyone's heads? I think you need to get a lawyer and absolutely not agree to any division of assets or visitation or anything at all until you have a lot more protections than you have now!