Firstly wait till you calm down then think about everythig again in peace.

You have every right to be upset, and i don't think youre overreacting, but divorce is a though process and if you decide to go on that path, do not rush it and start conversation angry.

I get a feeling that he doesn't respect you - thats why he repeatedly does things that he knew really upset you. And respect is not something you can just talk about and he will have it.

Maybe think about everything wrong in your relationship, and everythig that still makes you happy. Then about what can you do to make things right and then evaluate if it is worth a try.

what's left of our relationship

That tells me a lot how you feel about your relationship in general, and if thats still your opinion after initial rush of anger passes, then i doubt you can patch things up :/.

Disrespect, lack of trust - those sort of problems are likely to escalate, and considering you didn't manage to regularly fix them up untill now, they will.

Divorce will affect your son, but unhappy mother and unhealthy relationship will too. Probably more on the long run.

Thoroughly think about it, try to establish communication with your partner, see how much effort is he willing to put into making your relationship work, and if its because of you or because he just doesn't want routine to end/ affect your son with divorce

(My personal opinion, i got from one paragraph about your 10y relationship, hope it helps)