Is his female best friend terrible or am I just jealous?

My boyfriend has this girl he's been best friends with for years. I've tried to like her but she's... Terrible! She's not really rude to me but she's one of those friends he gets a kick out of embarrassing/bullying their friend. She talks about this scar on his face from an abuse thing and makes jokes about him winning an ugly contest. Jokes about his brothers death. Says some very person stuff. She yelled to everyone "Remember how you were totally in love with your therapist?!" He will ask her to stop talking about it and she won't stop. She said to me "Hope you know your boyfriend has been sucking dick since he was 8". He was pretty much forces to explain to me that his 18 year old babysitter made him perform oral on him. She then goes for his weight and calls him fat when he's not even fat. Just... Husky. He sat on a chair that was ALREADY broken and it broke and she said "Good job fatass" When he started to tear up she called him a cry baby. Then told me good luck because he's such a crybaby. I told him she's not a good friend and he said "Well she's the only friend I've got and my only family left". I get family doesn't have to be blood but even if she was blood anyone who treats you like THAT isn't family.