I know that with my DS, leaving him to cry, even for a minute, only makes things worse. Obviously other people have different experiences, but in our case it simply doesn't 'work'.

I'm no baby expert, but I'd be inclined to stay with him, and when he stands up, lie him back down. You might go through it 38 times, but eventually he'll get it. And just be so tired that he goes to sleep! I do this (was recommended at sleep school) and it works, although is exhausting! It does get better with time though.

Good luck, whatever you do, I hope it gets easier soon! I feel your pain