You really can't blame yourself for helping make something that wasn't designed for war but is used in it regardless. About as much blame as a guy in a shoe lace factory inadvertantly making laces for soldier boots. If you don't work at the war crimes factory, you've done what you reasonably can probably. At least vis a vis the moral requisite of trying not to support genocide. A guy that made Excel probably shouldn't feel bad if the US is using it to track their weapons shipments, right?