Hi dear I appreciate your support and concern to him, this requires till he cope with problems.
It's common most of the relationship break ups will be an emotional dysfunctional (betrayed) leading to the Depression. Right now your brother could be in severe depression, which requires immediate psychiatrist intervention. Further he can take the help of psychologists to work on his emotional area to cope from the negativity to reality of life, by building the self belief / confidence and values.
Next Steps
At the earliest take the help of both experts to deal with the situation, in the meantime your strengths is also important here, so that it can reflect in him also. Don't worry things will settle. Take care. ☺️
Health Tips
Put the environment with the things he likes the most and comfortable, focus and encourage on minute coping things also..