Sorry to hear of the loss, although it sounds as though you weren't extremely close to your friend and her husband at this time in your life.

This may have no bearing on your friend's situation, but my mom suffered from depression and took her own life about the time I graduated high school. Other family members did not want to explain the circumstances and told my grandmother that she died in a car accident. It was easier for them than explaining what really happened.

Regardless of the details, your friend may appreciate a card or call of sympathy, just to let her know you are thinking of her at this time.
Sharon