I think you need to separate your son's actual dx from your work decision. At 10, with a new dx, when as you say you have really known for the last 5 years, there will not be an awful lot of change in your daily circumstances that would warrant such a big decision. The actual new dx might make accessing support a bit easier, but it won't in reality make much difference to your lives at all. Lots of people find it easier post dx as it removes the 'is there/ isn't there'. Most people who are deciding not to work do it at a much earlier point (when it becomes clear that the child cannot cope in nursery/ school, or that they are having to spend large amounts of time off work for their child's medical appointments/ therapy/ mental health appointments/ sickness etc.)
That's not to say that you shouldn't decide to give up work for your own health - but it isn't really a decision that should be made 'because of' your child's dx. If you want to give up work, do it. You may well feel better for it yourself. But don't do it for your child. Do it for you if you are going to do it.
I've done both, fwiw. I worked weekends and occasional evenings when small girl was tiny (to tag team w dh), we also had live -out ft nanny for a year when I was working ft (my employer paid) and we have also used a combination of wrap around care (three kids in three different nurseries/ schools, with three different after-school clubs/ childminders). Obviously the issues with finding childcare and establishing routine are exacerbated with sn. We were lucky in that we moved a lot, so ultimately I had to reconsider every year or two in any case. Whilst it was harder it terms of having to get used to new specialists and therapy teams, and prepare kids for new places, people and routines, it did give me an automatic reconsideration point each time. This was before ds was dx. I wouldn't have given up work for his dx (that's not to say it isn't hard coping with him - just that it was equally as hard coping with him before his dx as after, lol).
Ultimately, think of it as a wider project. The actual dx won't change your situation much (it would be unusual if a dx at 10 meant huge changes in routine) but it could be used as a trigger for you to consider your own health more widely, rather than your child's. Don't do it for him. Consider if your own dx would benefit from a change.
(one of mine was dx at birth, the other at 9, so am familiar with the differences. A new dx feels like a decision point, but in reality when you have pretty much known for years it doesn't change much in your day to day. It just gives you a legitimate 'reason' to consider what you have been doing for years because you have a piece of paper. The actual 'doing' stays the same, but other people view it differently - if you feel you need to give others a 'reason' for giving up work that isn't 'I don't think I'm coping with my life'. So it kind of gives you a legitimacy. Your child is exactly the same. 
. If you needed to give up work the day before you got the dx, then you still need to the day after. If you didn't need to give up work before you got the dx, you don't need to the day after.
The sn boards are a good place to hang out if you haven't found them yet.