I am so, so sorry for your loss. Suicide is incredibly hard on families - much more so than natural death, or even death in an accident.
My uncle committed suicide at age 40 - he shot himself in the head as his kids stood outside the house waiting for the school bus, and his wife threw herself against the bathroom door screaming and begging him to let her in so they could talk.
My family has dealt with this tragedy in various ways. My aunt will probably never recover emotionally. My cousins seem to have managed to work through the issues, but their family dynamics will never be the same.
Overall, most of our family came to this conclusion, which I think applies to most suicide situations:
My uncle was certainly not "in his right mind." He definitely needed outside help, which he did not seek or receive, in spite of the pleading from his family over the course of the year or so leading up to this. But can we blame him for not getting help? I don't think so. Emotionally ill people don't often make logical decisions.
Can we blame his wife and kids, or larger circle of friends and family? I don't think so. Short of committing someone (which is not an easy thing to do), you just can't expect to be able to control every thought or action of a person who is suffering from emotional or mental illness.
From a theological perspective, I believe that God has great pity and mercy on anyone who would be so distraught and hopeless that they would take their own life. I definitely do not agree with the old school belief that suicide condemns one to hell, because it is a sin we can't ask forgiveness of. I don't believe that God is legalistic like that. I believe He knows our hearts, our fears, our griefs and sorrows - and I believe that He is more holy and just and merciful than we can comprehend.
I feel one hundred percent at peace with the concept of putting our loved ones in God's hands and allowing Him to exercise His perfect holiness and mercy on them. He loves them more than we ever could.