Tragedy Is Not a Competition: How to Talk About Boston?

How do I deal with friends who post things like, “Yes, bombing in the US is bad, but what we need to be talking about is the US sending drones to bomb other countries”? The same friend posted an article a few weeks back that said (paraphrasing), “Sure, there are issues with LGBT Americans, but most of them are well enough off that marriage equality shouldn’t be a big issue. While you were too busy paying attention to the Supreme Court, Obama signed a bill protecting Monsanto’s ability to grow GMO crops, and that’s a way bigger problem.”

I have a hard time reading these things and not feeling shitty about everything; they make me feel guilty for some reason. How do I respond? Is it even productive? Why can’t this friend just talk about their concern about drones separately from the Boston Marathon? Isn’t raising awareness about issues one at a time better than being elitist about the ones you think are more important than others?