I was/am the addicted wife, my husband uses no drugs at all, doesn't even really drink alcohol though he's been around (and works with) addicts all his life. I had many many years clean from before we were married right through having our children and it was only when we had finished our family and something traumatic happened (actually a string of things) that I fell into aeduction again and it took hold quickly.
It sounds like she is using opiates or maybe benzos/alcohol or all 3. That was me. I lied a lot, tried to hide it but he knew, everyone knew.
Where is she at in regards to talking about it/willing to do something about it? Even admitting she has a problem? This is key to knowing what to do I guess. If she knows and admits she has a problem then support her and make every way possible for her to get treatment. It's hard but try not to judge. Most of us don't set out to hurt anybody (except maybe ourselves) but it's exactly what we end up doing.
There are many paths she could take - short term detox and therapy, long term rehab and ongoing therapy, 12 step programs, suboxone plus therapy for either a short term detox or longer term maintenance if she feels like she is likely to relapse. Diffeeent things work for different people.
In my early 20's I did a longer term rehab, I did get some useful tools out of it though I relapsed and was in and out of the rooms of NA and only stayed clean to have my first (and subsequent) children. At that point in my life I had many years clean with the support of NA.
This time around i did a short term detox, I did feel like I needed rehab again but with 5 young kids and a business it wasn't an option. I relapsed and ended up on SUBOXONE and a very long and ongoing Benzo taper. Nearly three years in im still on maintenance, struggling but 'clean' apart from my Meds and the occasional weed I've recenlty started using (though have decided to give that a break as I can feel the pull of dependence.). While 12 step programs worked for me in the past, being on Suboxone they aren't an option for me now so im doing therapy.
The main issues for Husband have been trust. He was really good while I was going through my addiction and getting clean but a couple of years on all the mistrust and judgement came into play and it was so so hard living under suspicion everyday when I wasn't doing anything wrong at all. I saw the problem and fixed it, the ball was then in his court to deal with his trust issues as I had done all I could do. Addiction is messy and as the other party I guess you walk the fine line of supporting and enabling which isn't easy.
Best of luck, if she's using BENZOs particularly, don't suggest or let her go cold turkey as It is extremely dangerous. If 12 steps appeal to you. There are meetings such as NARanon for family members of addicts to get support from others going through the same thing.