Cut off the broken or crushed stem to a spot where you see healthy plant tissue. Do not leave a stump. Cut it flush against a stem or another branch, if possible. Use a sharp knife with a smooth blade.
Support a stem that is damaged by securing it with an elastic band to an unbroken part of the jade or a stake in the soil. If you can't wrap the elastic band around the branch, cut the elastic, wrap it around the stem and support, and tie the elastic ends together. The elastic band won't damage the plant, because it will move as the plant grows. Remove the elastic band when the stem feels solid again. This method can work on stems that are not badly damaged. A severely damaged stem should be removed. If you are unsure, try to repair the stem. If you see it softening or starting to rot, take off the band and remove the branch.
Care for the plant as usual. Now is not the time to change any of the parameters. Do not repot, add extra nutrients, water more or change the plant's location. This can weaken the plant, which needs to focus its energy on repairing the damage.