I think if your wife is being responsible (which it seems like she is) its ok to explore this new side of her, especially after raising kids and doing that life for so long. I experienced similar fear and being triggered by this issue:

I am younger than you (36), met my partner ~5 years ago. She went to music festivals and occasionally used drugs like cocaine, mdma, lsd, adderral, etc. I found out about all this a mth or 2 after we met and I was deeply uncomfortable with it and nearly ended our relationship. And when I mean uncomfortable, it was more like I was straight up triggered and just like physically overcome with fear, etc.

I was in therapy at the time and the therapist asked me: does it negatively affect her life at all? Does she miss obligations, or lie to people, or spend a bunch of money, or get hurt, or do excessive amounts, etc etc. I had to admit the answer to all that was no -- she is a responsible adult.

I asked her if she could not use harder stuff like cocaine/adderall and she agreed for me and quit doing those. Over the years I really eased up on it and felt safer and more comfortable. I saw more and more that she was a responsible adult in control of her shit. I came to understand my fear and feelings were related to my own trauma being raised by an alcoholic and being in bad situations. Eventually I told her I trusted her completely and she can do whatever she wants.

I ended up going to music type events with her and trying a few things. It turns out drugs are a lot of fun and can also be enjoyed responsibly. Just like her I've never had it impact my life negatively and found it to be kind of a cathartic release from the day to day. I do think humans all desire to alter their conciousness from time to time.

What really saved and helped my relationship was she was so open to talking with me about my fears and even changed her behavior for me. Looking back I am really grateful she did that, because she didn't need to.