Friends can most definitely be abusive.

I haven't had quite the same experience as you, not nearly as bad, but I've had an extremely manipulative friend when I was younger. Met her in my first year of high school, we quickly became best friends. I loved her like a sister. But she was jealous, controlling, spoiled, and thought I owed her everything. She was bad at socializing so she only had me and one other girl as friends, and she was extremely controlling and jealous of us.

She could also be VERY nasty - she always had snarky little comments meant to hurt us at our worst spots whenever we did something that didn't please her. She always had to be in competition with us - somehow had to prove she was better than us, happier than us, had more money than us, etc etc. She continually tried to prove her boyfriend was better than mines. At some point she even tried to fight with me about who had been in the country for longer (we're both Brazilians living in the US), as if that somehow made her better than me.

I told her every detail of my life because she was my best friend, but she used that information to manipulate me and backstab me. The last straw was when I moved into my own place and I was looking to buy some basic stuff, and she offered me this old microwave that her family didn't use anymore because they had a newer, better one. It was just sitting in the closet taking up space, she said. But she wanted me to pay for it, $40 bucks. More than it was worth, but whatever, it's still cheap, and it's from a friend, and after all it's only fair that I pay for it, right? The day we had planned for me to go over to pick it up, I was on my way, and she threw a fit - because my boyfriend at the time was driving me. She didn't want him to drive me and she wouldn't tell me why. She came up with this ridiculous plan where my boyfriend would take me back home, and another mutual friend of ours would go, pick me up, and bring me to her place, to then take me back home and THEN be on his way. I told her how ridiculous this plan was, but she wouldn't listen. I said, no, I'm going over anyway because I'm already on my way.
She couldn't stand not having things her way, so she called the gate and gave them my boyfriend's name with specific instructions to not let him in. She treated him like a criminal. We got to the gate and turned around, I left crying. I don't remember if I texted her then or not, but I went home thinking, "You can keep your stupid microwave, I never want to speak to you again".

That same night, at about three am, she sent me SEVEN text messages, explaining that the reason why she made such a big deal was because she didn't like my boyfriend's driving, and she was worried he would break the glass plate that goes inside the microwave, and I was asking myself, why the hell would that matter to you? I'm buying the stupid thing anyway, so if it breaks, it's on me! But she continued, and she said that she actually wanted the microwave back someday!! She said, ONE DAY, WHENEVER she got around to moving out of her parents' house and got her own place, she would want the microwave back from me... I thought this was absolutely ridiculous, if I buy something, it's mines, it's my money. You have no right to claim I have to take care of it for YOU because YOU want it back. If she wanted it back, she would've given it to me for free with the condition I give it back one day (to which I would've said no to anyway, but that way it would've at least made some more sense). And when I tried telling her, she seriously thought there was nothing wrong with what she did. It has now been over five years since the incident, and she STILL lives with her parents. This is how ridiculous her expectations were.

This was the last straw that broke the camel's back. I stopped contacting her, and when she contacted me, I ignored her. Several months passed by before we exchanged some bad messages through facebook, when she tried making me feel bad and guilty - I was spending new years' in New York and she was in Brazil. I posted a status about my friends making me watch a horror movie I didn't wanna watch, and she thought that was the perfect opportunity to brag about how her new year's was going sooooo much better than mines, and how miserable I was, etc etc. Real nasty and *****y. I tried telling her some of my thoughts and I told her I wish I had never met her. She replied with this nasty attitude, "Sigh, do you really think I'm going to take the time to read what you have to say? Let me think about this..."
I never replied, deleted, and blocked her. Never spoke to her again. Several months later heard from a mutual friend that she would like to be friends again but that I was expecting her to apologize and she would absolutely not do that. That was so funny to me, because she couldn't take a hint - like I would want to be friends with a manipulative, controlling, nasty, spoiled ****** like her again!

She ended up losing all of her friends, AND her boyfriend, because no one could stand her nasty attitude. This one irrelevant girl decided she felt sorry for her and decided she would try hanging out with her. Boy, did she cling to her for dear life! I felt honestly bad, because I thought the trauma of losing everybody in her life would finally make her realize and change, but this one irrelevant girl came in and ruined everything - because she enabled her to continue in her bad ways.

Nowadays I don't hear much about her anymore, but just like you, I still think about her here and there. I loved her like a sister and did everything for her.The little I had, I gave her, but all I heard in the end was "You never did anything for me!".

No one deserves to have a toxic friend like that in their lives. We're both much better off they're gone. ^_^