do i have the right to be upset?

There is a difference between giving a reason for why you did what you did and also acknowledging that you hurt the person unintentionally, and trying to excuse the behavior. This sounds more like the latter, giving an excuse followed up with a "but Im sorry" does not sound sincere. And then turning the card and calling you ablest when you brought that up.
Yes, you have a right to be upset, I would not continue to hang around someone who has a habit of hitting and punching.

The problem is that we are a friend group of 3 and the 3rd friend we have also agrees with this person that I was being ableist. It honestly hurt in my gut that they said that because the two of them have hardly ever taken my disability seriously. I suffer with chronic fatigue syndrome diagnosed for about 5 years now and they are always making jokes out of me for being lazy and using it as an excuse to lay in bed. My chronic pains are horrible and it effects me daily so it was like a big punch in the face that they said that.

Situations like these never end well when other friends pick sides when they werent involved.
It sounds like theres been quite a bit building, its not just this one incident then? Have you spoken to them about this? Not accused or attacked them, but explained how hurtful their comments are at times and how it affects you? If you havent, that would be a good start.

This all started when their mum said to them 'the doctors thought you had autism when you were a kid' and literally sinse then I guess we have just all assumed they have it I guess?? I dont know anything about a diagnosis and I dont mind self-diagnosing if you are 100% sure and are unable to access healthcare at the time. But I don't think that gives the right for them to put autism over my disability.

I first asked them to stop making jokes about my hair, as i suffered with really bad thinning after my stress from depression last year and when I opened up to them about it. They stopped for the most part but now and then they still throw it in which hurts. They also joke about my skin being bad which they know has been an insecurity my whole life. Another thing is that both these friends suffer badly with worries about their weight. After all these different jokes they make about my insecurities and me asking them to stop it made me wonder how they would react if I retaliated. I made a joke about liking my waist shape (i didnt mention their bodies whatsoever) they told me that joke made them want to (tw suicide) k*ll themself and that it was a disgusting joke to make. I literally didnt even mention them in it at all....I'm assuming that it's just impossible to set boundaries now and that I will forever be the one to make fun of in the group