Stuffitllama I think that was very harsh.
If the op is unhappy in her marriage and has been for quite a while, that will impact on her family. In many ways her dh and son will pick up on how she feels. Staying in a marriage because you feel obliged to makes for an unhappy marriage imho. I've seen firsthand what eefcts it can have - on children included, and it often leads to one or more feeling utterly miserable - for years!
Why shouldn't the OP be happy? Why shouldn't she give her dh a chance to be happy with someone else? OP, you wouldn't be taking your son away from your dh, it will be different but he's also at a young enough age that he'll grow up understanding that mummy and daddy don't live together anymore. He will adapt, as will the rest of you.
From what I've read there is no bad feelings between you and your dh, and it sounds like you do care a lot for him. I think it's great to see that you're still willing to work at your marriage. But please don't beat yourself up for how you feel, you're only human.
Nobody deserves to go through life feeling miserable in a situation that can be changed. Keep working at it, but if it doesn't work out - don't beat yourself up. Things will always work themselves out one way or another.
'I think your name is quite accurate. Romantic feelings are not the most important thing in a marriage and for the sake of your son you need to at least try to find a way forward within your marriage.' Seriously
Maybe I'm being slightly romantic here, but I was always under the impression that loving the person you are married to was a pretty big part of the deal. And as far as the op's son goes, it's my belief that you shouldn't stay in a relationship just for a child's sake. It does nobody any good ime, and just leads to everyone being unhappy.
beanieb made an excellent point at the end of her post.