It doesn't sound good really. He might be trying to think about how to respond to your message. So a lack of response at this point isn't something to worry about.
If he doesn't say anything about it when he gets home, that's another issue.
Having said that if you've got in a state where communicating is difficult, then it won't be easy to broach the issue.
You've both been through some major stress recently, but his behaviour sounds a bit extreme and he doesn't see that there's a problem. That in itself is a big problem.
Have you just bought a house or rented?
I only ask for a because his behaviour is also that of some men having affair. Especially the lack of interest in sex, but if you'd purchased a house in the and he's having an affair with that seems to be a big commitment for someone not all in.
He has fun when out with your DS, but not just the two of you... So it looks like his issue is with you. Is he moody with his friends, family or anyone else like this?
My suggestion would be to stop trying to initiate sex with him.
Start being more independent and consider learning how to drive.
When he gets into a rant and shouts, don't respond. Just say nothing and carry on doing what you need to do.
Try doing an activity independent of your DH.
You are much too young to be so dependent and you leave yourself vulnerable by being so dependent.
The more dependant you are, the more you feel the loss and struggle to function if the relationship ends.
If you can, ask him if he still wants to be married, because his actions don't seem to show that. Go one further and ask if he'd still want to be married if you didn't have DS.