I do think that you are in danger of over egging the pudding here. As far as I am concerned the war was a wrong decision although considerable mitigating factors can be put forward in Blair's defence. In all other aspects we had thirteen years of decent government with improvements in education and the NHS. I would be the first to admit that I dislike Corbyn, however if I thought that he could win I would be wholeheartedly behind him. However I am convinced that he is going to lose, and badly. In 2017 he was buoyed by Remainer votes. Due to his (at best) ambivalent attitude to Brexit that ship has not only sailed but lies with the fishes.
Name one mitigating factor. It was an illegal war, with no UNSC resolution backing it. The premise of WMD’s was false from the start, and 16 years later, no evidence of them was found. A maverick group of MI6 agents were believed and, despite other agencies telling him not to go, Blair’s hard-on for the war won through.
I can’t speak for education under Blair, but I have several friends who were senior teachers who, in the end gave up due to the mindless SATS bureaucracy. It got worse under the Tories, but Blair didn’t help. And let’s never forget that Blair introduced tuition fees!
As for the NHS, I worked in the NHS before, during, and after Blair, and the relentless drive towards privatisation, PFI’s, impossible targets, lack of resources, lowering morale, and increasing waiting lists continued seamlessly throughout. True, we had Agenda for Change, with parity of pay-grades between different professional and non-professional staff, but most staff ended up worse off and having to work night shifts for no extra pay.
Your dislike of Corbyn, who is a decent, honest socialist (3 words which no one would use to describe Blair), masks the fact you have given up on the Labour Party, which is a great shame. As someone (apologies, can’t remember who) said the other day, Labour activists are fairly accustomed to being behind in the polls, but that’s never stopped them from campaigning.
I do agree, however, that Corbyn’s stance on Brexit has been shamefully divisive. He honestly believes we would be better off leaving as long as the deal passed the 6 tests, but that ship has long sailed. There never will be a Labour deal now, so the only real choice for Labour is to unite around a People’s Vote, something which Swinson appears to have turned her back on now. That fact might even work in Labour’s favour.