She is absolutely not seeing anyone else. I know this for sure.
How do you KNOW this? She told you so?
You situation and the words of your partner are SO standard issue. Not to be argumentative, but so is your response. Read how many threads around here where two weeks later the person in your position says - how could I have been so blind. You guys were all right on.
EVERY single sentence is standard issue affair crap.
Find out what you are dealing with. Come back and tell us we are wrong. You can smack me first. Seriously, we've seen it so many times before. Knowing what you are up against will help you more quickly figure out what game plan you need to implement and 1)break you out of limbo and 2)start taking your strength/life/control/self-esteem back. You might also get your mate back in the process. Where this crap is concerned, the fastest way, one way or another, to end the pain, is to move straight forward.
Me 44 She 46 S13 D9 M18 T23 3 years DB'ing Successfully busted