Every day I get a glimpse of that, and by far, you are not alone.
It used to be unbearable to me, however, I have learned some new techniques to work around that.
First of all, you understand that BPD gets much better over the years, right? In case of severe depression, we have to always look out for alternatives in order to control the disorder - there's no cure.
Have you looked into good old psychotherapy? I've read a book from David Burns, "the feeling good new mood therapy" that sounds sooo cliche but its quite interesting! It encouraged me to look into that treatment rather than meds - which I haven't taken in many years.
I made small and big lifestyles changes, and honestly, I see a gigantic change in my life. Exercising regularly improved my self-esteem, as well as avoiding certain social behaviors that are not fit to us who suffer from mood disorders - like drinking alcohol regularly, for instance. Small unimportant things, like sipping a cup of tea in the morning, walking through a bridge,... it all counts.
When it comes to people, It will always be a learning process for us. My mechanism is to lower expectations for everyone, so any good that comes is a pleasant surprise; any bad thing is already expected. I confess that I need a lot of improvement in this area, but as long as we keep moving forward and seeking for our well being, that's all that matter...

Best,
CF