What can i do if bro-in-law is financially punishing us for consequence of his misbehavior?

My bro-in-law is the eldest of my husband's family who in his defense, did take care of his family following their father's death some years back. However, he has solely, but not legally, spent and reaped the benefits of the family inheritance. He had a mistress whom he spent much money on, and as a consequence, he is in the process of a slow, financially painful divorce with his wife who must have had enough of his selfish ways. Over the years, through what he has inherited and earned, he took care of my mother-in-law financially, who herself had made some unwise investment and lost everything. But then, my husband and I have come to a place where we can financially contribute to her livelihood and started doing so by sending her some money for her daily expenses. However recently, my husband and my brother-in-law have gotten into a fight (caused by his unreasonable demands to give him money and send him new Apple and other pricey products). Very petty indeed, but the issue was getting more serious and financially burdening by the day. So far, we've already sent him 5- ipads (why this many?!), 52-inch flat screen tv, unnecessary electronic gadgets, and too many things to list in this posting but he still wants more. These demands for money and expensive products used to occur in a frequent fashion, but things took a wild turn when he's decided that unless we meet his demands, he is no longer going to support my mother-in-law. We already pay more than half of what she needs monthly. And with this new threat, we are getting forced into wiring more than a thousand dollars a month. My question is, do most people pay over a thousand dollars for their parents per month? We are typical middle-class family, fortunately without a child under this circumstance, but I am afraid of having one now with this much financial burden. Secondly, is it unreasonable for me to be angry with my brother-in-law? I feel as if he is punishing us financially for his mistakes. He insists he can't save because we aren't paying the support in full, but he used to pay over $1000 for his love-nest with his mistress, traveled with her internationally, and lived a lavish lifestyle (he still does), and he now has added expenses to pay alimony to his wife (in the process of divorce) and child support. And he is now blaming us for his financial issues. I just want to sever any ties with this man. He treats my husband so poorly, it makes my blood boil. He may have acted as a father-figure following their father's death, but unfortunately with so much financial and moral irresponsibility. Perhaps I just need to vent and this forum is serving as a venue for me to feel better and relieve myself from anger. What seemed to be a threat to cut financial support for my mother-in-law (unless we provided him in full to his demands) isn't a threat anymore and has become a serious punishment for her and us. We provided everything he wanted and he still pulled the plug, which we now are left with no choice but to pay in full. He has no rent/mortgage since he lives in the house that was left by his father, he owns a business that he funds with the inheritance, and spends money in ways we can only dream of. But yet, all the financial burden is on us. We live strictly on our earnings, living a happy but a humble life. What can I do to stop my brother-in-law from tearing us apart? I don't want the family to split apart. But can I talk my husband into severing ties with his brother? I am an only child and my husband's brother makes me so glad that I don't have any siblings (although I know most people don't have brothers like my husband). Is there someone out there with a similar situation? How are you handling it? Please share with me your wisdom.