Easiest thing to do is to replace the broken spoke and true the wheel. If you have a lot of time on your hands, you may de-tension the whole wheel, replace the broken spoke, and retention everything back - but many on this forum may feel that the juice is not worth the squeeze.
As for spoke tension meters, I've got a cheap Chinese version and I've been happy with it. If your rim isn't good to begin with then you'll get really inconsistent readings across spokes, but at least you'll know.
Last edited by tFUnK; 03-30-24 at 02:40 AM.