Except that Labour is pro-Brexit. I have no confidence that Corbyn won't renege on the second referendum.
It doesn't matter whether you have confidence he won't renege, you
can have confidence that Boris
won't. And, at the very least, you should be able to have confidence that Corbyn will want to negotiate a softer Brexit than either of the last two prime ministers.
You should also bear in mind that Labour almost certainly won't get a majority, meaning that Corbyn won't be able to force anything through. The third-largest party, who he will most likely have to form a coalition with to become PM (assuming no Tory majority), will most likely be the Lib Dems and their position is to revoke Article 50 all together. Likely other remain parties, as well. So if Labour's position moves, then it should be slightly more towards "remain" than towards "leave".
The point is that it seems somewhat silly to hold the position that you don't trust Labour to cancel Brexit, so you'll happily hand the election to the Tories who definitely won't. If you honestly think that Brexit will be bad for the UK, then you should vote tactically to get the Tories out. The Tories not having a majority is the only possible way for Brexit not to happen, and if it
does happen for it not to be the most harmful Brexit possible.
My entire life I've voted for whichever parties policies most closely match my own opinions. Not this time, because there's a unique catastrophe in our near future and the
only way to prevent it (not to mention all the other horrors this very right-wing government would foist on us) is to get the Tories out of power. And the only way to do that is for everybody to vote tactically.