It's important to approach this situation with sensitivity and respect for your partner's autonomy and well-being. Since she has returned to her parents and you mention that they have demonized you, it's crucial to be aware of potential complexities and challenges.
Respect her decision: If your partner has chosen to return to her parents, it's essential to respect her choice, even if you disagree with it or feel hurt. People's decisions are influenced by many factors, and it's vital to recognize her right to make choices for herself, even if you believe they may not be in her best interest.
Focus on your own well-being: Going through a breakup and dealing with difficult circumstances can be emotionally draining. Take care of yourself and consider seeking support from friends, family, or a therapist to process your feelings and emotions.
Communicate openly (if appropriate): If there is an opportunity for communication, approach it with understanding and empathy. Be honest about your feelings, but avoid pressuring or trying to persuade her to come back. Respect her boundaries and emotions during the conversation.
Encourage professional help: You mentioned that your partner has untreated BPD, which can be challenging to handle without professional assistance. Encourage her to seek therapy or counseling to address her mental health concerns. However, remember that ultimately, the decision to seek help lies with her.
Consider the patterns: Reflect on the dynamics of your relationship over the years. If there were issues or challenges, consider how they may have contributed to the current situation. Self-reflection can be helpful for personal growth and future relationships.
Give her space and time: Healing and making significant life changes take time. Allow her the space she needs to work through her feelings and make decisions without pressure.
Learn from the experience: Regardless of the outcome, use this period to learn and grow as an individual. Relationships can teach us valuable lessons about ourselves and what we want in future partnerships.
Remember that each situation is unique, and there may be factors at play that are not apparent from the information provided. If you find it difficult to cope with the situation or your emotions, consider seeking professional help to process your feelings and experiences.
Ultimately, the decision to get back together or move on is one that both of you need to make independently. It's crucial to prioritize your well-being and mental health throughout this process.