You guys were really helpful and hit the nail on the head with a lot of your statements. As I posted this her and I "dated" each other (didn't live together) for over 2 years. We moved back in together May of 2012. She started acting different immediately after. She got even better at hiding affairs and her affairs became even more reckless, she had a stalker showing up at work with the police getting involved.
My beloved SIL who helped her with a lot of these affairs introduced her to this guy. I never found out until months later. We split up In December of last year. Thank God it's over. She is now with her last affair partner. The comment about nostalgia and remembering how things were was exact. It's all behind me now and life has been amazingly drama free. My mind isn't 100% back to normal yet but it's really close. Life moves forward