Q.Struggling Christmas Cactus
My red Christmas cactus has been struggling for over a year. The shoots of cacti are wilted, and nothing seems to strengthen it, not even plant food. I read that it may be unhappy in its soil, so I repotted it the beginning of the year. It perked up for about two-weeks and then promptly fainted. It has been this way for months. It has no bugs. When I looked at it this morning, it seemed as if the main stalk is dead. It was dry, crinkled, and frail, so I might have to detach and root the branches in order to save whatever is left of the plant. How do I do this?

Repotting can help revive a struggling Christmas Cactus.
Too large of a container though can make the issue worse. They prefer to be a bit root bound so choosing a slightly larger container is the best option.
Over watering or root rot can also cause a wilting plant.
These articles will help you.
https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/limp-christmas-cactus.htm
https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/christmas-cactus-flower-wilt.htm
https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/christmas-cactus-root-rot.htm