You have to distinct and separate issues here - one is related to your work and the other is a personal issue.
Regarding the work issue, you need to be careful. You say that you "want" to be involved in this issue and "believe" that you should be involved, but is it within the scope of your job to be involved? AKA - are you going to be sticking your nose into other people's business by doing so? And also remember that there are always 2 sides to every story - if it is your job to hear both sides great, but be careful about sounding an alarm if you don't know.
Regarding how to detach from this kind of thing at home or away from work, I'm still working on that myself...but I find that walking, reading, playing with my kids, really anything to get my mind on to another task helps quite a bit.