Don't mix "уж" and "уже". The first one is a grammar particle and not a word proper, it doesn't convey facts, but more like personal opinion of the speaker. The latter, however, is a proper word with clear meaning of passing some threshold/mark (usually in time, but sometimes in some kind of a row)
"Уж" is a modal particle, i.e. it gives an emotional opinion of the speaker. The exact meaning might vary greatly, but usually is something about annoyance of the speaker caused by inability of the other party to grasp a very simple idea.
In this particular case I tentatively translate it as "and it is your fault, you moron, that it is a very bad idea to to X do, and you should see it easy enough", but I need more context to be sure.
some random paper about the particle: link . If you can read it, it should give you an idea.