I'm not sure there would actually be a point to listening to music with detachment, but then, I'm biased, being a musician whose sole purpose in playing is to revel in the emotions that music stirs up.  If you feel overwhelmed by negative emotions that are being whipped into a frenzy by certain pieces, that suggest to me that you are normally sublimating a lot of negative emotion and when you listen to music is when your psyche is attempting to let that all out.  If you are really afraid that you will commit violence because of this, then you really ought to find a counselor that is trained to help people find an outlet for these feelings, but I think that you have already found the trigger that gets the emotions flowing.  Perhaps you ought to take up a very physical activity that you can perform while listening to this music, such as running, that will let you work off this energy until you are spent, without denying yourself a needed release of emotional expression.  If I were you I would look into drumming.