>>1Trust me, you can't both appear as a decent guy, and not see your girlfriend when you break up. Just do it man. The important thing is what you say to her, so you must prepare to present the reasons for breaking up with her. You can't just go "it's not you it's me", you'll have to be more decisive than that. Remember, there won't be an opportune moment where everything works to your advantage, so you just got to seize the moment.
One time I broke up with a girlfriend while her shirt was still covered in my cum, so you might want to avoid that. Like you I had planned the breakup for some time, but I finally decided to just come clean (so to speak). But again, you might want to do it a bit more tactful.