Is it possible you felt abandoned by losing your mother? And people with bpd almost always have a fear of abandonment. I would think it is connected, and that you may have run away (as you call it--abandoned a family member) from this difficult situation because of your own fear of abandonment and the recent experience with losing your mother. That is just my guess. I know you are not to blame for these losses and difficult family situations. It is completely not your fault and was probably a self-preservation instinct that kept you from losing it. Be easy on yourself, and know you are a loving person.