I am fed up with my sister in laws?

I have been married for 3 yrs , but till now facing sister in laws problems which is never ending. My Father in law is a puppet in their hands as they always make him senti as they lost their mom 3 yrs back. My husband is the only son and they are his younger sisters. My FIL has given them more property share than us b ut still these girls are like leeches who sees every opportunity to take money from u s...i know im bit bit rude but that's the exact feeling i get by seeing them making us spend always giving reasons that their respective husbands don't like spending money... I have tolerated lot of problems just because they lost their mom and thinking i need to take up her place...but these girls took advantage of that and started playing foul games and i am fed up...i had almost gone into depression seeing that even after giving so much love. they complain about my small mistakes to my FIL and he calls me in front of the entire family and makes me ask sorry to their daughters which i feel very hurting...He is basically a very good person but gives lot of importance to his daughters words and spends even if he knows its utter waste..My husband is a silent spectator and says its his money and he can spend his way...i sometimes feel that is it wrong to to feel bad seeing money getting drained away...does this happen in most families...im really not sure...can any one of you help me plsss...im in great need of your words....