My mom is unbelievably rude to my friends. What do I do?

Sometimes my friends' moms will raise there voice at me, you know? But I brush it off my shoulder, no big deal. But my mom is very different! Like today, for example, she called my friend a liar to her face! Whenever I have sleepovers, we usually order pizza for dinner. My mom expects my friends to "pitch in" all of there money for the pizza- if they don't, they can't eat. She also insults my friends, and their parents, right in front of them! She says cruel things like "What bad parenting" and "She's always late". She'll make fun of them, and act like it's a joke. If my friend asks for food, she says "Go get your own food, you live down the street." Sometimes she even'll say that we aren't a homeless shelter! She even says that some of my friends are poor. When one of my overweight friends eats to quickly, she'll call them, sometimes me, a pig. She told me and 4 of my friends to get out of her house, and called us "Jack Asses" again, to our face. When she took a few of my friends and I to the beach, she refused to buy my friend a cheap snack. My friend hadn't eaten since breakfast, and my mom knew that! If my friend doesn't have money, she'll say "to bad" in a mean way. Once she almost ran over my neighbor, and didn't apologize. When my neighbor's grandma came to talk to my mom about it, my mom cussed her out and told my other neighbor/best friend that she was a brat. She's made all of my friends cry at least twice- even her best friend's daughter! On the other hand, I try and talk to her about it, and she says "to bad" and goes and hides in my dad's room. My dad doesn't try and stop it because he's afraid to- I think he's soaked some of my mom's behavior up, too! He always says no to things, and says "bummer". Anyways, my mom is even telling my friend's 8 year old sister to go home and feed herself. I'll remind my mom she's only 8, and she'll say that she's old enough to know better. To sum it up, I'm not sure why she's mean to them! They're not mean to her, and my friend's parents are really nice to me. I've started to treat her bad because she's mean to me, too! We've tried family councilors, but they don't work- my mom makes my friends sound like monsters, which they're not. My mom always has to follow the rules! For example, for some thing- I don't remember what- you had to have someone 14 years or older ride with you to go on this one thing. My friend who's almost 14, was going to ride with me, so it'd be okay; even the manager said it was fine! But my mom, HAD to complain, so we ended up canceling it. Don't get me wrong, it wasn't just that time. There's been more- way more! A side from that, she says I have tummy problems. For the past 10 year almost, she's been "researching" and going to doctor after doctor, complaining about my tummy problems! They all tell her I don't have them, but she doesn't listen; she just goes to the next one. In the meantime, she puts me on strange diets to help me lose weight- no citric acid, no milk, no gluten, no sugar, etc. The experts say it's not necessary, but she doesn't listen to them. All my friends hate her, and there parents, literally. I'm even starting to hate her! Thanks to her, I already have a nasty reputation and even nastier rumor going around about me all over the school district. I'm loosing friends every week it seems, and some of my friends even pretend they don't know me half the time! All answers are appreciated. Thank you! I want my mom to be nice. :(