First off, sorry about your mom.

The friends who are suicidal, you need to talk to an adult about right away. If not a parent, tell a counselor at school or a pastor that you trust or some other adult. The friend may be angry with you at first for "telling," but will be grateful in the long run. It is better to have a freind mad at you than have them dead and living with the regret for the rest of your life.

Has your mom talked with anyone, any type of counselor or doctor, about her emotional issues?