Where do you get the strength to go on?

Taking one day (or sometimes one minute) at a time. In this case, try NOT to look down the road.
Just as they cared for us when we weren't able to make decisions, we sometimes need to do that for them too. Unfortunately that means that you've got to take the decision making away from them. She certainly wasn't able to do anything while hallucinating. Try to explain the reasoning behind your actions and include her in on as much as possible. Ask for her opinion on different things so it seems you are still "learning" from her and relying on her guidance. Thank her for helping you.
Gosh life is hard. Pray a lot.

Old Sailor, great suggestion that Owl is doing this so no one can take her mother. Owl, following on OS's suggestion, you're taking the ultimate action to protect your mother from those who might seek to exploit her.

I began reading the article you referenced but couldn't finish it b/c it was so upsetting. Perhaps some day when I can handle reading about extensive abuse of individual rights...but it addressed so many abuses, such flagrant disregard and exploitation of seniors...it was just too much to contemplate. I was becoming so angry as I read it that I stopped, for my own health. I didn't want to have a heart attack or stroke.

As to your initial question, I think we have to find a way to get downtime, to recharge our emotional and mental batteries. Sometimes other things just have to be put aside. I've found that gardening magazines are so relaxing, and re-invigorate me. I read them when I do laundry, so it makes a less than enjoyable chore more pleasurable, and repositions me for going back to the caregiving grind.

What would you do if you had more leisure time?

I would also explain to her that you are taking this action (guardianship) so no one can take her away from you.

I posted this link a few days ago. I don't know if it will help you or not but here it is again:

https://www.newyorker.com/magazine/2017/10/09/how-the-elderly-lose-their-rights

Owl, you're not doing this "to her". You're doing it FOR her, so that she can be cared for properly, so that you're enabled to do that for her.

I know that it in fact does represent taking a lot from her, and it's hard to emphasize the obverse, that you're enabling yourself to do things for her, not for yourself.

Perhaps you can think about all the reasons why you want guardianship, how it enables you to care for her to ensure that her care is the best it can be under the circumstances. If you can offer examples it may help.

Can you also create special treats or events for her? Doing something she likes, so that she doesn't feel as if she's being stripped of her rights?

After the guardianship hearing, I'd take her to someplace very special, someplace that makes her feel loved and benefited, not stripped of her rights?