I'm sorry for the situation you're going through. While I'm off Active Duty now, I have some advice as well. I'm at the tail end of divorcing an alcoholic and it has been brutal. Our marriage problems started two months after we tied the knot when she cheated on me, with a former groomsman, while I was away TDY. I forgave her and we had three sons together, even though the cheating continued. Even though the divorce is emotionally tough and financially draining, I'm honestly happier than I've ever been.
My advice:
1. Always think about the children's best interests (if you have kids), and never make it about you or your ex or your problems. Never badmouth the other parent to your kids, because they will figure it out in the long run.
2. Push for 50/50 custody (legal and physical) of your kids if you can. Kids raised with equal time are far less likely to have substance abuse problems in the future. I'd be happier if my kids were primarily with me, but I'm very fortunate, as a man to have my kids week on week off.
3. Realize that money and stuff is just money and stuff. I gave the ex everything on the list she wanted, but I am fighting tooth and nail to prevent alimony. What I mean here is that you will likely blow through all of your assets and be in debt at the end of the divorce. Even worse if you have to pay alimony and child support.
4. This really should be number one. If you are thinking about divorce, I guarantee that she is already twelve steps ahead of you. Document everything and have witnesses who will testify to your character as a parent and a spouse. See if your STBX is willing to move out and go to rehab. I told my ex that if she didn't go to AA, then I was leaving her. Her parents could also be one of your biggest allies if you play your cards right. This is a slam dunk for custody.
5. Start listening to every podcast (dadsdivorce, etc.) or videos on youtube. You also need to understand how the law works in the state you're in.
6. Hire a private investigator if needed. The thousands of dollars I spent equated to cinematic gold that will be shown in the courtroom (I live in an at fault state).
I could put about 1000 things on this list, but you can PM me for any more advice. Best of luck to you.