oh man that was me 2 years ago.... i was so convinced she was up to something i made this ellaborate plan to make her dump me... and it worked it BLEW for about 3 months... then i was like "was i really happy with her?" no. now i am happy as hell... best thing you can do is have a real heart to heart with her none of this "lets be together forever" bullshit.

do a diagnostic on what worked and what didn't maybe telling her why you cheated and why you think she woudl get back to you would help? basically waht you are doing with us is what you shoudl do with her. best thing to do is make sure if its done its done and you can work it out on your own or if its gonna try to work then you can try and make it work. this playing both sides will only make it suck more.

and for getting rid of the pissed off feelings may i suggest weight lifting or paintball or something where you can break things/throw shit around and its ok. good luck