Entitled mother-in-law refuses to pay back thousands of dollars to her daughter-in-law because she’s going on vacation

For example, say they need to get their car fixed, and it costs thousands. They don't have the money, so they borrow it from you, and give it right to the mechanic. In their mind, they barely even touched that money, because they gave it away. Now, they're resentful that they have to pay you back, and they also can barely afford to do so, since they didn't have the funds for it in the first place. 

It'll make things much more pleasant if you just pay them, and then never think about that money again. 

But this woman is stuck in a super awkward, and increasingly volatile, situation with her MIL. Her hubby's away at bootcamp. And the MIL is about to leave for a trip… even though she still owes quite a lot of money to her DIL. The audacity!