You should have a serious talk about separating with him. See what he has to say. If he says in no uncertain terms that he's basically in the marriage for your child's sake...then yes, let him go. Not only for him, but for your child.

I'm a Christian, so I am generally not a proponent of divorce. But I can't imagine that being toxic to one another is something anyone, whether God or the state, would want for married couples...

I know it's an extremely difficult decision to make. I'm grappling with the same problem in terms of whether to let my husband go, but the circumstances are different. The idea that we would not be together is extremely difficult...but at the same time, the old saying "if you love something, let it go" exists for a reason...