How do I prove that my girlfriends husband is responsible for killing himself and his fellow soldiers?

He along with two fellow soldiers was seriously wounded while trying to diffuse an IED and died 2 days thereafter. I think that he was too depressed after learning about our affair and wanted to take his own life since he had 5 years experience disarming all sorts of bombs. I think the families of the other soldiers need to know the truth about what transpired. What do I do?