How do you get someone to forgive you? when you have borderline personality?

Forgiveness: You can't make someone else forgive you. If you have hurt another - a sincere apology accompanied by remorse would be in order. However - equally if not more important - is that stop the hurtful behaviors. Having a personality disorder is not an excuse for harming others.

You can't. : This is a difficult one. Despite how difficult it may be to tolerate someone being upset with you, each individual has a right to their feelings. It will be important for you to practice learning to tolerate your discomfort because you can not make someone change how they feel. That is neither fair, nor possible. DBT is always a good way to lean these skills.