Hi hvert

What an unpleasant situation! I don't have exactly this sort of experience to draw from, but I would like to encourage you that, especially as this lady has other support people in her life, there's no need for you to feel guilty. It's a healthy thing to have and respect your boundaries.

And it seems to me that you're not rejecting her because she's become boring but withdrawing because her behaviour leaves no room for friendship. Sure it would be good if someone helped her recognise this ... Maybe someone has? Would she be open and able to work on it now?? I think, if you feel you can tell her why it no longer feels like a friendship to you and explaining that her behaviour makes it impossible for you to enjoy her company then great; if not, it doesn't have to be your responsibility. Especially as you're not leaving her lonely.

Hope that helps!