I Must be a Dependent Idiot

My long-time girlfriend/now wife has quite a history of cheating, but I never seemed to be able to catch her in the act. Actually, I'm probably guilty of not going through the relatively simple procedures in order to catch her out of fear that I'd have that image seared into my brain forever. However, knowing the truth and witnessing it with my own eyes may be worse than living with the gnawing and unrelenting suspicions, the lies and the near certainty of her infidelities. Just to be clear.... Multiple texts from some guy who couldn't wait to meet with her again, seeing emails from another person on a hook-up wibsite who also was found to be on her phone's speed dial, dozens of quick screen changes on her computer from ones which had the typical photos of available people on dating sites, absolutely no sex on a weekday night (and sex at all has been reduced to maybe twice a month in a girl who professed to want it several times a day) and I've caught her multiple times in her office parking lot under Super-suspicious circumstances, both with head-shaking, juvenile explanations. At an office party, I was dumped seconds after a man showed up who I heard whispering "hi" to her behind my back at a point when he didn't know who I was. They spent the next 45 minutes elsewhere and ultimately at another part of the huge property. I could go on including the nighttime visits to the bathroom with her cell phone, the midnight texts, the cell phone obsession and dozens of other incidents, but you get the drift. How do I convince myself to leave? I really don't Need to catch her because she's been statistically caught many times. To still be here after years of agony and emotional punishment must mean that I'm insanely dependent or emotionally insane. I don't even know why I'm writing this because the answer had been whacking me up aside the head for years.