'Nearly 40' - that's a big milestone and most of us I think have had to look long and hard at life when it's a Big Birthday.
'work 30 hrs+ a week and have 4 yr old with Atypical autism'
I'm ASD myself, so I know what sort of hard work I can be even as an adult . And having had a son with probable ASD, I know what sort of hard work he has been in his younger years too. You're not working 30+ hours a week, you're working about 600 hours a week, by the sound of it. Well, you know what I mean.
Who gets to do the washing, cleaning, shopping? I bet it's you?
'I feel like giving up, there is nothing at all to look forward to in life and I am totally unrecognisable from the girl I used to be.'
Yup, a trip to a trusted GP might be an idea. You've got so worn down that you need a break of some sort. If that's not happening because of stroppy and unco-operative people, you need a boost of some sort from doctor/counsellor, or some respite care from the council, or something - anything - to give you some 'me time' back again?
Have a cuppa. It's no consolation, but it's a start...