It may be that your child is more sensitive than you think… some children are natural readers of any strong emotions or tensions in the room… the feeling may not be coming from them, but they pick up on it and act on it.
I would recommend spending bonding time with your child… walks are a greet way to do it… or any other movement based activity that releases endorphins and can be done together. Even playing catch with a simple ball in the garden!
You want your child to associate with you fun activities and the release of good feelings.
Father needs to be more active in this… if he has time for “hobbies” he needs to make time for his children, I mean actually prioritising them. Have him take the infant even if it’s just for an hour while you play with your son or take a break.
We need to break this cycle and the first thing is how you feel….you sound defeated, upset, frustrated, and a bit angry and despairing.
There is hope! Strongly consider talk therapy with a psychologist and short term medication to relax you so you can take it all in and start on a new page of feelings.
ND or not, your posssibly highly sensitive child won’t be happy until your are… the more relaxed and content you are, the more he will be, too…
I know it’s hard to imagine right now, but sometimes and action precedes a feeling… for example, forcing a smile when you don’t feel like it, actually releases happy hormones and helps to rewrite the brain!
Similarly, playing catch might seen too simplistic to solve your worries… but try it and see, I guarantee you will be surprised how both you and he feel even with just ten minutes a day!
Sometimes we psyche our own selves out and lock ourselves into a little box in our mind, when the solution is a very simple action.
In short, think and worry less, do more (fun physical stuff that breaks a sweat) together and apart, too. You both need some healing and playfulness in your lives.