Something I have found useful from AlAnon is the acronym "FOG" - Fear, Obligation, Guilt.
I have learned that if I am doing something because of the FOG, I probably shouldn't be doing it. It's only going to cause resentment and pain, now or later.
If you don't feel like going to their "mandatory" classes, you don't have to. I think a lot of the time they try and pressure you into that sort of thing so that (a) there's the "Look at all the rehab is doing!" feeling (for their benefit) and (b) to educate the family on some of the realities of addiction (for the addict's and family's benefit).
You don't really benefit from the first point, and you're already actively working on the second as witnessed by you finding this forum.
I would not say not to educate yourself about addiction - you need to so you're ready to deal with things when she gets out! - but there are other resources available like SR or AlAnon that will work better for someone with a busy schedule if the rehab will not work with you.
Maybe take off work on Monday for the first day of their training, just so you have a starting point on the rehab's input into things, and then work the rest of the week? Or whatever works for you. You don't have to commit to the whole thing all at once if you feel the resentment coming on - it would be less beneficial. But give it a shot for a day, and you can decide from there.
You're allowed to take care of yourself, and rehabs aren't a one-size-fits-all sort of arrangement. The rehab XABF went to was supposed to limit his time on the phone to 5 minutes a day (per their own rules) but he'd still call 10 times a day for 20-30 minutes at a time to try and rule my life from inside. I complained to the staff, who told me he shouldn't be able to do that and didn't believe me when I said he was. They wouldn't help, his in-rehab therapist wouldn't address the issue with him, so I had to come up with my own solution which consisted of blocking the number and not talking to him at all.
Rehabs are more versed in addiction treatment than we are, but that doesn't mean they're always right or that they know what is best in a particular situation. You need to do what you need to do to take care of yourself, and sometimes that's not the path the rehab wants you to take.
Keep in mind, too, that rehab is a business. They're being paid to worry about the addict, not to worry about you, so their priority is going to be on what they're being paid for. Nothing wrong with that as long as you keep your needs in your priority list, and if there's a conflict you're allowed to come first.
Speaking of which, she's somewhere where she is safe, now is the time for you to take advantage of that and learn to breath and re-center yourself on you and your needs. She's got paid professionals looking out for hers, you can take a break from that. (This is another reason I am a firm believer in rehab).