MindReader I am so sorry your DC is having such a tough time. It must be heartbreaking to see them so disenfranchised from education so early.
As a PP has suggested, i have given up on primary and am looking ahead to secondary. I feel very fortunate that the school she will go to is fantastic at supporting those who don't find learning as easy or as straight forward. Learning is not a 'one size fits all'.
it helps me that DD1 is at the school, and although she is the other end of the spectrum, i have been able to have chats with her about her friends who have the same struggles as her sister. The main things that have re-assured me is there is alot more differentiation at the secondary, and this doesn't necessarily mean being written off.
DD1 has many friends who, with help, are managing to progress really very well. And friendship groups are varied too. there seems to be less stigmatization as teenagers don't often compare levels and test result (too much else to gabble about!!)
I think I am also more reassured about DD1's secondary because it doesn't stream, but sets instead. So, hopefully, some subjects will boost her confidence because they are less reliant on her weaker subjects. DD2 is a whizz at languages, so DD1 has reassured us she will be in top sets for french and spanish (based on what she has seen, and knowing that DD2 already excels at these out of school).
Also what has helped DD2 is her dancing. She knows she's a fantastic ballet dancer, and knowing that while she may not be the best at academia, she has her strengths elsewhere. You say your DC is a whizz at computers, maybe they will have the confidence to join an outside club where your DC's strengths are recognized, and where they are able to compete on a more even playing field, and feel their skills are recognized.