I echo what others have said about a Risk Assessment and contacting the EIS.
My experience is secondary. I was told that a child with profound learning difficulties would be joining my S1 class, because the parent had complained to the Director of Education. The child had been in mainstream for primary, but the case had been made that they wouldn't cope with secondary.
The child's learning difficulties were caused by a genetic condition. Non-verbal, but did grunt from time to time. On top of that, they were registered blind.
The classroom teachers in our school were all mainstream trained only.
However, a TA was allocated to work with that child only. At the very least, I'd say that that is the provision that you should have for your pupil, OP. Two to be shared with the class is no use - my class had a second TA or sometimes SEN teacher allocated for the rest of the class. We could cope because the learning difficulties of the other children were moderate at most and it was a smaller class, half the size of the norm.
Nevertheless, it didn't work out. I'd already written reports to say that the child was doing no work. The region had bought in a specialist computer programme, but the TA was doing all the work for the child. (I'm still baffled as to how a child who could only follow bright light was supposed to access the work on the screen.)
The parent finally agreed that the child could move to specialist provision after I had to write a report about them masturbating in front of the other children.
The point I'm trying to make is that - given what you've told us - mainstream is not the place for the pupil you've mentioned, OP. As a mainstream classroom teacher, you can't be expected to magic up resources for a pupil with profound needs.
Mainstream didn't work for our pupil, even when one-to-one was provided. You've been placed in an impossible situation.
Thinking about it, if you have to write up your concerns, you might mention that there's no space in the WTA for you to provide a differentiated programme of work which articulates with all aspects fo the CfE for this child. (As I used to tell staff, the WTA doesn't just work in favour of management.)
If you have to go off with stress, do it.