do you have a shotgun certificate or FAC...........if so
lock up your valuables
be very careful how you get rid of her
if you do it badly....she might use your gun ownership against you
get you mrs to dump her on the pretext that she is taking on more duties in the home........give her a finishing "drink"......something like a couple of teabags in an evelope...and do as suggested ....go to a acredited agency......