Hi there, and
yours is a difficult situation, because when it is your loved one or a child of yours, you would do anything for them. A friend is very important, but you are not supposed to adapt your life to them, and it must feel like she is overstepping your boundaries.
In some emotional levels, a person with BPD is like a child. They test your boundaries, and they push you and pull you, and they are really terrified of being alone, and more than that of being abandoned.
On the long run, it would hurt you both if you changed your plans for her. You need to be able to follow your goals in life, and to keep true to your values.
As you care about her, the most important thing you can do is to validate her feelings. Recognize her fear, her need of you, her suffering... .Take a look at the lessons in this website about validation. If you can watch the fruzzetti video, you'll have a better understanding of it. It doesn't mean you have to like it or agree with her, but you recognize what she is going through, and how she fells about it. You can also reinforce that you care about her, and assure her that you are coming back (and when), and, if true, that you are going to keep in contact with her.
She is probably ashamed of this "clinginess", and her pain of missing you, her insecureness of her importance to you, the lonelyness, and that shame go incircles feeding each other until her emotional pain is unbearable. That pain is real, even if you are not abandoning her for real at all. And she experiences any feeling a hundred times stronger than us.
It is not your responsibility and not your fault. Feeling guilty is not going to help anyone. Accept the situation as it is, and do what you feel you can do, without compromissing your own values and needs. Does this sound right?
