Brother in law has always lurched from one failed venture to next and always turned to (younger) dh to bail him out. Around four years ago, he emailed dh to say he was in 'trouble' and needed 60k. We were aware at the time that his dp (who is now his wife) knew nothing about him being in 'trouble', or that he had asked dh for this 'loan'.
Despite my advice to the contrary Dh gave him the money on the condition that if he ever desperately needed it back (eg school fees) it would be repaid in full. He did need it very badly at one point but BIL only repaid 1.5k. He has since married his partner who has somehow come into a very substantial amount of money, and they spend half their lives on cruises.
I have no bad feeling whatsoever to my SIL as to this day she is unaware of the situation and would no doubt be shocked if she knew. Dh has 'written off' the money and chosen to forget about it because it is his brother and he is a real family person, but every time we see them I can't help but feel contempt for BIL. I'm sure it shows as unfriendlyness and SIL probably wonders why. I couldn't possibly tell her as WW2 would break out and I would not want the finger pointed at me for possibly wrecking their marriage. I just can't understand how BIL can look dh in the eye.