I hate being married to my wife
I  have been with my wife  for 8 years, married for 3, and we have a 6 year old child together. I want to start this off by saying I know that I have made mistakes. I wish I would have known (or admitted to myself) sooner.
Our relationship started off differently than most. We met online and due to circumstances of studying abroad we couldn't meet in person for 15 months, when she came back home. We ended up forming a relationship anyway with daily skype calls lasting hours, texting, facetime, etc. We met each other 15 months into the "relationship", moved in together 3 months later and 6 months after moving in together she was pregnant. Not my finest moment (more like year). We had been talking for so long that I felt like I knew her and loved her, but really I didn't. You can't know someone from a screen.
As soon as that pregnancy test showed two pink lines I knew we had made a mistake (she didn't see it that way). I tried to step up and do the right thing. We had our daughter and life went on. My wife brought up marriage and engagement all the time. She really wanted to be married and I constantly blew it off, changed the subject or straight out said no. She was miserable and embarrassed, she felt like I didn't love her, didn't want to be with her, that she wasn't good enough, wasn't attractive enough, couldn't do anything right. Some of it was true... I didn't want to be with her. But we had this child and I wanted to keep our family intact, solely for that reason.
When we fought I'd say/let it slip that we were only together because of the child. My wife got upset and I'd take it back. I didn't have the balls to walk away.
We did get married along the way. Completely on a whim and I regret it. We went to city hall, it wasn't what she wanted at all. She wanted the big dream wedding, I just wanted to get it over with. I'm at the point where I just cannot do it anymore. I hate being married to her. I try to slap on a happy face but I'm not winning any acting awards. She thinks that I just don't like her, not attracted to her, etc. She has been fighting for this marriage for so long. She is always on her "best behaviour" to try and make me happy, she initiates sex and I just turn her down, she tries new things for me. She thought it was because she gained some weight (10lb maybe) and started starving herself. She's a people pleaser, she always has been, and in her world nothing she does can make her husband happy. It's me, not her. I never should have married her.
It was never as clear to me as it is now, that I can't be married to her. I recently got a different job and there are a couple women who are interested in me. I haven't acted on it, but that doesn't mean I don't want to. Telling her I want a divorce will hurt her enough, I don't want to add an affair on top of that.
How do I break this to her, or do I suck it up and deal with an unhappy marriage and try to make the best out of it? She is a really good woman and a great mother to our daughter, but she isn't the woman for me. I feel horrible and I know I'm a jackass. She is the perfect woman for someone, probably a lot of men, and I feel like I'm ruining her.