Ugh... My former marriage was something similar to this, but I never cheated on him. He, however, cheated on me. Only once, to my knowledge, very shortly after we were married. I had gone to visit my parents for a week or two and it happened while I was there. He told me about it after I returned, and showed me a letter she'd written to him. She'd been one of his first loves; she freaked out after they got physical and I think ended contact with him immediately after. He'd never gotten closure on that, and probably still loves her to this day; he got back with her immediately after our divorce, and she was bat-shit crazy jealous of both me and a mutual friend of ours, as our breakup was very amicable and we spent a good amount of time together for a number of years after, which I think it was good for our kids. He broke up with her after a relatively short relationship, and to my knowledge hasn't been with anyone else since. We'll have been divorced for 14 years in a couple of months.

I was actually never in love with him. I loved him, we were close friends; he was very much in love with me, and I thought something was wrong with me that I couldn't reciprocate that deep feeling. I became pregnant just over two weeks after we became engaged - about two months after we'd first made love, which was my first time; I was 21. I believe I never would have gone through with marrying him if I hadn't become pregnant with his child; I nearly left him at the alter, and might have done so if we hadn't married in his parents' house. We were married for eighteen years, and had two children. Our marriage was much better than many I've seen where both parties were very much in love at the start. I always felt guilty for having married him, knowing I wasn't in love with him and never would be. He was, and still is, prone to depression and anxiety; I never would have been able to leave him because of all this and my belief that leaving him would send him into the deepest depression ever, so I made the best of it. I constantly fantasized about what it would be like to be single again (I'd only had a few very short relationships before him; I appeal to a very small and unique set of men, and the Venn diagram of that set and the very small and unique set of men who appeal to me is quite minute), but could never do anything to make that happen. But eventually, he filed for divorce because he was clearly on track for a third major depression, largely due to the fact that I simply wasn't capable of giving him the affection he so needed. He filed over a month before telling me, only telling me when he knew the papers would be served soon and he felt he had no choice. A friend was very angry that he filed without talking about it with me, in effect, completely blindsiding me, but I understood all too well that he couldn't do it at all unless he took that irreversible step; I can only imagine how hard it was to actually pull the trigger on that.

Every time I hear the song, "Better Man," by Pearl Jam, it makes me think of my marriage. But for the record, I can't say I regret our marriage; we have two wonderful, now grown, kids, and now a beautiful granddaughter. I was raised in a very conservative and closed-minded household and he opened my mind and gave me a huge respect for learning as much as one can about as many things as possible, without expecting to be monetarily compensated for that knowledge (my parents never understood the value of knowledge beyond using it as a means to making more money, and the fact that I never attained my degree has always been a huge point of contention for them, even though I've had a pretty decent career without it, as did my father without a degree, in the same field). I can only hope that my ex got as much benefit out of it as I did...

I don't even know why I'm saying all this, as it's not truly relevant to the thread. But your story seemed to parallel the story of my marriage, with a few things switched around, so there it is.