How should we react? Reaction is not a choice, it is an automatic response based on conditioning. The question needs be, How should we ACT. Then we will have a choice based not simply on one of our basic emotion of "wanting to get even," but on a more rational response.
Obviously - in the long term anyway - "bombing people back to the Stone Age," as a particular politician said about the undeclared war in Vietnam, will not guarantee victory. We know who won that war. Deployment and victory by armed forces must be backed up with something more.
We know that 'punishing a people' such as the Allies did to Germany at the end of the 1914-18 'War to end all wars' dies not work. However, the various Aid schemes implemented after the 1939-44 war were much more successful. Deal with the civilian population; get them on side seems the way to go.
In the case of world-wide terrorism, if the terrorists tacitly have the support of many, they'll keep at it. If that support is nullified by having the people who support their actions not only no longer do so, but who revile THEM, rather than those the terrorists are at present attacking, things will change.
When violent acts are deplored worldwide then the violence will die a natural death. But in order for that to happen a whole cultural shift will need take place; probably the biggest change in Human History.
So if you wish for that change there's really only one person you can work on - yourself. As President Truman said, "The buck stops here." If enough of us do that, then the change cannot not come about.