I'd still keep a good system in place to prevent another mishap and just in case they do show up, but yes, it happens, and she didn't seem to be reacting badly, you stayed up to watch. You have the numbers for poison control, 911, you're aware of the medication itself as you take it and so does your son, so you're not totally unfamiliar with the medication itself. You knew the likeliest reaction was that she would have trouble sleeping, the worst would be a possible allergic reaction (and you were right there to call 911 if that did happen), but you stayed up and made sure she was okay, and she was okay. You now have a system of some type to prevent it from happening again, so all is good.
We've all mucked it up now then (morning medications at night or vice versa, examples you've seen above, etc.), and I'm sorry your so-called support group was anything but and way high-strung. I'm sure you can find other support groups online (and off FB where you can be more anonymous) that might be more help for your bi-polar.