The mama bear in me wants to rage

I won't go into full detail cause it's very very long. But basically my husband is currently not talking to his sister because of her own self. She's the one who blocked his number and blocked him on social media. She also blocked me which is funny considering I stay out of it but whatever. My husband is also looked at as the "black sheep" of his family. He's the only one to graduate college and make something of himself. Basically out of 3 children he's the only one who doesn't need mommy and daddy to support him/us. And for whatever reason that bothers his mom? I haven't figured that one out yet.

Today his mom caused a big uproar when she asked my husband if his sister were to send out oldest son a bday gift if we would throw it away. Well words were exchanged about how my husband doesn't need his mom buying a gift to make his sister look good, that if she wanted to give him a gift she needs to grow up and give to him herself. And his mom, my MIL, had the nerve to say "well I'm just looking out for (our child's name)"

Which has me pissed off, they basically just lost all my respect. Like don't use my child as a pawn in your drama. Our children don't need looking out for, they live in a very established and safe environment compared to his sister and niece. I'm just fuming over it. I know I'm probably overreacting but my husband has done nothing wrong besides tell his sister she's making a very stupid decision on being with a guy who is not stable and has already used her once and then threw her and her daughter out on the streets once he got all her money. But she still ran back to him. Not to mention again, his mom is always baby-ing his sister and everyone has to walk on eggshells around because "that's just how she is" when really she's just bat shit crazy and doesn't take her medication for it so then it's like everyone has to cater to her.

I'm just so over it.