I can relate to this so so much! I'm currently in the process of (most likely) cutting my (old) best friend out of my life. We've known each other since we were 9 and are both now 23, but she's very toxic, selfish, etc. Around 2 months ago I finally decided enough was enough, snapped, somewhat went off on her through text, and have been avoiding her since. Our only contact has been a few texts trying to figure out when to meet up to "talk about things" or "figure things out," like she wants to do. She seems to pretty much believe this is just a fight that we're gonna get over, and not just the final straw making me finally actually decide to cut her out of my life. I kind of want to just be done with it, but since it does feel like an unfinished way to end such a long close friendship, I've agreed to meet up with her and talk, probably tomorrow. I'm nervous, because it's going to be uncomfortable and I've told myself it isn't worth the effort, but also because even though I'm determined, a small part of me is so worried something will happen and I'll wanna go back to how things were and undo the work I've done the past 2 months.

So, sorry for babbling about me, haha, anyway! I can relate on both feeling more freedom, and feeling like no one is even close to the same and wanting to go back.
It's helped me to focus on the wrong things she's done and why she's toxic, and realize that though I kept justifying it in the past, it is bad for me and can't keep going on. It might sound messed up, but it's almost like if you try to focus on the negative and gather up the "anger" you feel at that person for things, it can help when you're really missing them or really tempted to go back.

Also, if you're really sure, just 100% decide and tell yourself you are not allowed to contact her again, ever. It reminds me of other times with guys/past romantic things. Times might come when you get all up in your feelings and really feel at the moment that talking to them is a good idea. You just have to decide ahead of time that you absolutely won't do it, that it's not even an option anymore.

It might also help to take this as an opportunity to focus on yourself more, and feel good that you've done something good for yourself. I'm trying to embrace the increased independence and celebrate the fact that, while of course there's the whole crappy losing a friend part, cutting out that negativity and toxicity is technically positive progress. You also might want to take it as an opportunity to socialize more and try to seek out some new (better) friends now that the attention and time you've spent with her is free.

Good luck with things.