Ok..i can tell you this much that..he has no right to ask for your jewellry to be sold to fix his finances. Why dont ya help out your husband by working or getting job somewhere. Everything has solution..as long as you are not stuck up and willing to work out solution with him.
Re: Husband help
It is a bad idea to sell jewellery to take care someone Else's financial problems. If you do, it will be very hard to buy/accumulate it back.
Also, if you have been paying zakat on this jewellery, then it is completely yours. You should do what many others have said here. Take it to your mom's or put it in a locker; don't bother discussing it with your husband.
If your husband has been paying zakat on it, do the same, but be sure to consult and convince your husband.
Re: Husband help
When BIL loaned your husband the money, was an arrangement/agreement made as to when and how those funds were to be repaid?