I’ve been going through the same thing with my husband for the last few years, and it is really hard, I won’t lie. However, I am in a much better place now than I used to be. I handled it very poorly for a while and said and did some things that probably only made it worse, unintentionally. Sometimes I think the more we try to help fix things, the worse we make them. So I had to spend a lot of time learning some tough lessons in getting out of the way and giving it over to Jesus.
As far as advice goes, I would suggest getting a Green Scapular, having it blessed, and then hiding it in something she carries with her often, or a place she spends some time (I hid one for my husband under his side of the mattress). Make sure to say the scapular’s prayer every day for her; the Green Scapular has effected many conversions, and I believe it will work for our own spouses, although perhaps taking many years.
Another thing that has benefited me greatly is speaking about the situation with some holy priests I know. Their counsel and insights have really helped me change my thinking and way of approach to the situation-- in effect, taking the focus off of me and my feelings of hurt and betrayal (not an easy thing to do, I know), and learning to pray and sacrifice for my husband on a consistent basis. I try to serve him in his situation where he’s at, letting God handle the spiritual side of things.
Your wife is on a journey, and it may be that she needs to take this detour and travel the long way home, but don’t lose hope. My own father stopped going to Mass for many years while I was growing up, and veered so far off the path that I was very worried about where his soul would end up. But my mom prayed for him every night and didn’t push, and my father came back to the Church and received the sacraments shortly before he died in 2009. All things are possible with God! I will keep you and your wife in my prayers.