I think I'd have some more counselling focused on this particular realisation. It's important to think and talk it through thoroughly before making any permanent decisions that impact your child.
I don't want to make light of this too much but is it possible that you are simply feeling trapped and wanting the polar opposite of your DH? You have gone decades thinking you are straight so although it is possible to suddenly realise you're gay, it is worth considering where this feeling originated.
God knows I've had relationships where I've seriously thought about whether life would be easier if I liked women but that was a reflection of my unhappiness in that relationship, not necessarily my sexual orientation iyswim.
In addition to the counselling, if I were you I would separate from your DH. I'd ride out the waves, let the dust settle and spend a year just being single.
No relationships, no dating, no hook ups, just concentrate on your son and find out who you are. Your son doesn't need you together. He needs stability but stability doesn't have to mean cohabitation and from the sounds of it, you need space.