Linda, killing off a queen was one of the hardest things that I have ever done too. It goes 100% against my grain. But like Ben and Ross both told you, you must think of the colony as the most important thing, the queen is destroying/holding back the colony, she is not doing what she is supposed to be doing. The is the ugly way to look at it, but if you can look at it in this way, you will kill her with a smile on your face. Believe that or not. It totally changes the way that you look at this gal, when you think that you have years for this colony to carry on, and you want to work with them, you want the best gal for this job, not one that you have a hard time working with, and so on.
When I kill the queens, and I have had to do this several times, I think to myself, "you tried, you failed, your colony is suffering" it become easy. Do as Michael says, a little tiny container with alcohol in it, drop her in, she dies within seconds, you must think of her as an insect, take away that human emotion that is holding you back. Beautiful day in this great life we all live and share. Cindi