Why wouldn't you break up like a man? It's so much easier to just get it all out, be honest, and move on. Trust me, women recover from this a lot faster than men, She'll collect up your letter pictures and burn them. She'll go out and buy some condoms hit the clubs and get on the carousel, and you are forgotten in a week.
The key is to be painfully honest... women always know when you are telling the truth. If you don;t want to talk about it, just say "You do know why we are ending this don't you? Do I really need to come out and say it?" many times this will be enough for her to back off and vent at you for a bit. Just sit there and take it like a man, but don't back down. You are there to break things off... nothing should steer you from that purpose. The last thing you want to do is to leave that meet-up with her still thinking there might be a chance. That REALLY is not fair to her... AGAIN TRUST ME, once she knows it's over she will bounce back pretty quick, and she'll be rubbing other dudes in your face in no time. Toss her a bone when she does this and act a little jealous... it costs you nothing and makes her feel really good.
You do not have to be an @ss when you break up with a woman.