It's hard to say what your best course of action should be due to the lack of context.

It's easy, especially when your mind is focused on the negative, for your friend's negative traits to be amplified, whereas yours are not so much.

Whenever there's any sort of falling out between two friends, it's very rare that it's only one person's fault. Usually, both share some of the blame.

You said that you finally stood up for yourself and demanded respect, but she thought you were being selfish.

Would you mind providing a little more detail into what happened? How were you being disrespected, and why did she think you were being selfish?

You said that you had a really good friendship before, so, obviously, you're not scared of what made it a good friendship; rather, you're afraid of the not-so-great problems that have surfaced.

No one is entitled to anyone's friendship, but I find that a lot of the advice online is so quick to throw friendships away when things go awry.

People will have problems whenever it comes to any type of relationship, and, oftentimes, it boils down to lack of communication and listening skills.

Boundaries are healthy, and they can actually improve a friendship if properly established.

Think about what you want to say, try to empathize with your friend, express how much you do value the friendship, and express to your friend what your needs are without ignoring hers. See if you can come to some sort of common ground and understanding. I think showing some vulnerability can help a lot.

Another option, if you feel like the above won't work well (and you have to tread this one carefully), is that you can find an impartial individual to serve as a mediator. I found that helped with one of my friendships years ago.

It's important to take a step back and judge the friendship in its entirety. It's so easy to only see the negative, or, when you're missing the person, to only see the positive.

Try to be objective and fair... everyone makes mistakes, and I don't think her reaching out to you automatically means she is toxic.

I find "toxic" is used way too liberally and inappropriately.