Thank you for sharing your question with Alterhéros.
You explain that early into puberty, your fascination with women changed to one for men. You dislike this part of you, but know you cannot change it. However, you are emotionally more attracted to the opposite sex and would like to build a family with a wife, but are afraid you will be unfaithful because of your physical desire for men. You also mention that most guys you have dated did not become serious relationships and that most gay men are too gay for your liking.
First of all I'd like to mention that it's perfectly normal to be confused about the things. You'd be surprised at the number of people who question their sexual orientation because they are attracted (physically and/or emotionally) by both sexes.
You say that part of you hates the gay side of yourself. Do you know why? Is it because homosexuality is still seen as a bad thing in society, or does it have to do with you desire to have children? Finding the answer to that question might make it easier to accept yourself for who you are, and therefore making the whole situation a bit less painful. I'd also suggest not trying to box yourself up in a category: straight or gay (or even bisexual). I think sexual orientation should be understood as something fluid; you are attracted to people, sometimes physically, sometimes emotionally, sometimes both.
You say that the guys you have dated turned into sexual flings. How did you meet these guys? Often, bars and clubs are good places to meet one-night stands and such, but not so good for serious relationships (though it obviously depends on the situation). Meeting people thru friends or certain dating websites might allow you to know what the other person wants beforehand. You say the gay men you've met are too gay. Have you thought about the fact that you just might not have noticed the other, not as obvious, gay men? I'm not sure where you meet guys, but in a social situation it might be easier to detect someone gay by their appearance. There are gay men who will fit what you are looking for, though. The too gay, looking for sexual flings guys are not necessarily the majority.
Your main concern seems to be about having kids and building a family. It seems to be very important to you that your kids grow up with a mom and a dad. Many families are parented by same-sex couples and are neither dysfunctional nor detrimental to the children. In Canada, it's legal for same-sex couples to adopt children. If you want more information, I would suggest visiting the website Family Pride Canada (http://www.uwo.ca/pridelib/family/) and seeing the documentary Our House (which also has a website: http://www.itvs.org/ourhouse/index.html). It might give you a different view about same-sex parenting.
You say that you are afraid that you might be unfaithful to a woman because of your physical attraction to men. You also seem to view yourself as a gay man, even though you don't mention if you have ever been emotionally attracted to men. Would you like to build a relationship with a man? Can you picture yourself spending the rest of your life with a woman? These are questions that you should give some thought to, but I also think it will depend on the person. You might meet a woman to whom you are very attracted to physically. And you might also meet a man with whom you would like to build a family with. The only advice I can give you on this is, don't limit your opportunities. You're still quite young and situations will arise that may change the way you view family, sexual orientation and yourself.
I hope this helped a little! Please don't hesitate to write back if you have any questions.