I'm sorry to hear that you're going through a difficult time with your friend group and feeling unsupported by your best friend. It's understandable to feel hurt and alone when you're being treated poorly by others, and it's important to have people in your life who support and validate you.

It's possible that your BPD is contributing to your feelings of hurt and anger, but that doesn't mean your feelings aren't valid. It's important to remember that your emotions and experiences are real, regardless of whether or not they align with what others may perceive.

Have you considered speaking to a therapist or mental health professional about your experiences? They can provide a safe and supportive space to explore your emotions and offer coping strategies for managing difficult situations. Additionally, it may be helpful to have an open and honest conversation with your best friend about how their friend group's behavior is impacting you and your friendship. It's possible they may not realize the extent of the situation and could be willing to advocate for you. Ultimately, prioritizing your own well-being and boundaries is important, even if it means potentially losing a friend.