You're not a bad person. You may very well have BPD. Thinking you're a terrible person deserving only the worst in life is definitely a trait of those afflicted with the condition.

You can't blame all your actions on your condition, but accepting that a lot of the destructive behaviour you exhibit is because of BPD should help in the process of taking responsibility for your actions, but not blaming yourself.

The mere fact that you are concerned about the relationships you've lost and the damage you cause shows you are a good person with insight. The responsibility now is yours to do what you have to to gain control over your condition - be it seeing a therapist, going on meds or making amends with the people you've hurt.

But above all, you are not a bad person.