Why did my ex friend call me a bitch for standing up for myself?

This girl who is my ex friend used to treat me so bad, manipulate me and always gets angry when things don't go her way or when I do something wrong she yells at me and treats me like shit. Took advantage of me because I had money. I tried to help her with things and she would yell at me for being "lazy" and claim. that she is doing all the work. She called me big fat and useless and I called her out for it and we kept arguing. When I almost broke something. She pushed me out of the way and yelled, "Get out of here! Go up to my room NOW! YOU WORTHLESS UGLY FAT USELESS PEICE OF SHIT! Not trying to be rude but you're are careless! Then I FINALLY stood of for myself and she was shocked. Then she told me, "Stop being so rude to me. SHUT UP LAYLA!!!!!' Thrn I told her, "No YOU shut up! I've have it with you!" I asked hee wby she treated me like this. Then she flat out told me, "Because you LET me. When are you EVER going to stand up to me. I've been waiting for you to so that but you're being a bitch. Then all that she called me a BITCH and said, "Get over yourself BITCH!" And she shoves me out of the way and stormed off.
She NEVER apologized for how she acted. Never.
She knew I have aspergers and had trouble speaking up for myself.

My best friend called me out for sticking up to this girl. She said, "I'm not trying to offend you but what were you thinking being friends with her? I've been trying to get you to dump her ass but you were too clueless to do it!" My best friend can be so blunt and bossy sometimes. She gives me a hard time about my wrong doings.