To dream that you commit suicide suggests that you have run out of ways to deal with certain problems or issues in your life. None of the methods are proving to be successful. It's possible that you are feeling remorse and instead of expressing those emotions, you are chastising yourself. On a more positive note, it may imply that you have found a way to discard negative emotions or qualities.
To see someone commit suicide in you dream indicates that you are worried for their well-being. Pay attention to the attributes this person may possess. They may represent similar aspects of your own personality that you want to get rid of. Maybe you detest this person's qualities and believe that if you possess similar traits, you want to discard them as well.