What to do if i have bpd(borderline personality disorder)and i am really depressed sometimes but sometimes i'm not?

DBT: Make sure you are properly diagnosed. Individual therapy is indicated. DBT (dialectical behavior therapy) is the treatment of choice. I would recommend the DBT in a group therapy setting in conjunction with the individual therapy.

Treatment: is likely to help. But the diagnosis can be controversial, so you need to see a professional that you trust. Usually a combination of medication and individual psychotherapy works best.