It's hard watching someone you love fall into anything toxic, especially relationships. The hurt in this can be felt. May she come to her senses and change her situation for the better.

This is utterly heart-breaking, even in the opening lines:
"The smell of your smoke still lingers,
reminding me of one more thing that you refuse to give up."

While I think people can have the power to change, it's important who and what they continuously choose. And shutting you out, mistreating you, etc was a choice they made and have to deal with. You will never owe them anything. And who people decide to be with matters and definitely represents their character.

I feel that surge of anger, then recognition in the last few lines. There's almost a sense of closure, or at least understanding, in letting yourself feel the anger and process it, knowing why and how it came to be. This is personal, though it feels all too familiar to me in regards to someone choosing a toxic person over you, and the neglect and hurt that ensues. The line that hit me the most? "you are not my guilt". That phrase is so crucial and, though I'm sure it's a hard realization, I hope there is some healing in separating from them and doing so for your own mental health. You mentioned empathy earlier, and I think that's incredibly human, to still have that empathy (though there's nothing wrong if you don't), yet knowing there has to be boundaries otherwise they will try to keep pinning things on you. Now, they have to sit in the hurt and pain that has been passed down, and process it for themselves.