I feel every word in this piece. And this here is absolutely what you must learn to be! Kinder to yourself.
You went over and above for this friend. And I understand why. I understand your loyalty and empathy. But sometimes there is only so much you can give and then it all comes crashing down.
Take a deep breath and move on. If she wants to show up in your relationship and make an effort great, but this is now on her. We all have struggles. We also all have the choice as to what we do about our struggles. She is choosing to sabotage herself and her relationships by the sound of it.
Thank you for this piece and I am glad you have realised you need to be kinder to yourself! :-)