Dab, message me on steam if you wanna talk about this more thoroughly
This isnt a good situation, but it can be fixed i think. She lied to you about doing drugs etc and thats what you're most hurt about. Trust is an amazing thing, but when you lose it, its really hard to gain it back. I smoke weed occaisionaly, and i used to smoke a lot more, I also used to smoke cigarettes and dip tobacco, and my dad caught me multiple times with cigarettes, dip, vapes, and recently about two months ago he caught me coming home from my dealers with 4 grams, and it had been a good couple years since he had caught me with anything, mainly because i stopped using drugs and tobacco for a while. He wasn't upset about finding the weed, but he was devistated because he knew i lied to him, and trusting a liar is hard and you often lose that trust, and again its hard to gain trust back but its a process. In my case, i stopped doing drugs and stopped lying to my dad, my family is really close and family oriented so trust is a big thing with us.
If she is confident and determined about stopping drugs and alcohol and lying to you, keep her because she is giving up something that she is most likely addicted to, to stay with you and make things between you and her better. If she seems on edge about quitting, that is normal due to addiction and should go away once the substance is out of her system, but if it doesnt go away and you sense she is still sneaking around you, you don't deserve that man.
And don't forget that you are in the Military, Darren. If you marry her and she moves in with you on a military base or while you are active-duty on a base and she gets caught using drugs, you and her will be in a lot of shit in most cases. My brother is in the air force and his wife got caught smoking pot, which isn't anything major and he wasnt too upset about it, but he makes 100% sure that she is not smoking while she is at their house because it is on their air force base. When she comes back to michigan where our family and her family is, me and her go chill at her grandmas and smoke, because then she isnt risking getting caught using on military grounds, and my brother is fine with her smoking when they're back up here. Be smart about this, and don't be too hard on her, she loves you and you love her, if shes worth keeping, keep her.