Q.Help With Desert Rose With Broken Stem
Can you advise me what to do with this half broken stem? Cut and propogare? Can I seal it back together? Leave it?

Certified GKH Gardening Expert
If you were to wrap it when it first happened, then wound repair would be appropriate. Since it has been awhile, I would leave it as it is, or tie it up, slightly.
It will continue to grow, and adjust to the injury. It is no harm to the plant, but might be a little unsightly.
Here are some articles that will help you with the care of the plant:
https://www.gardeningknowhow.com/ornamental/flowers/desert-rose/page/5