There's a lot here. You aren't happy with the situation, but you don't want to split up your child's home. I wish I could tell you there was an easy cookie-cutter solution, but that isn't real.
IT's obvious you aren't getting your needs met. I couldn't tell from your post if you think he even cares. It sounds like you and he have fallen into a routine. That is common after the first child is born, sadly. So much energy goes into the baby that you don't invest any in each other.
The message for the past few years is do what makes you happy and the child(ren) will adjust. Since divorce skyrocketed in the 1980's, we now have quite a bit of good data. Unless there is violence, neglect, or extremely high levels of conflict, most children do better in a home with both parents. The data simply hasn't supported the idea that kids in one-parent homes do just as well. Children whose parents aren't together are much more likely to live in poverty, suffer physical abuse, and suffer sexual abuse than are children in two-parent homes. Also, they are more likely to have educational problems, be arrested, become pregnant unintentionally, and to require psychiatric care.
Divorce, and that's what this would in effect be, is often a permanent solution to a temporary problem. Among people who reach the point of divorce but don't, in five years 85% describe their marriage as "happy."
Ultimately, this is a conversation you have to have with him. You also need to develop a support network of girlfriends. Having strong social ties helps us through just about any form of stressful situation.
You need to let him know that you're to the point you're thinking of leaving. He's probably taking you for granted and you need to let him know that it isn't working. I don't mean in a threatening way, just as a statement of the facts. People sometimes wake up when they realize that divorce is really a possibility.
If a split-up does have to happen, it will be easier on the child now than in a few years.