Hello Nymeria,
Welcome to the group, sorry that you had to find us but happy that you did. You will find a lot of NON's here that have been where you are, experienced what you have and some still trying too. but others will give you some guidance based on their experiences. There is a lot to learn and I would like to suggest a book to get you started. "The Human Magnet Syndrome". I would also suggest to seek out a good therapist to help you on your journey of self discovery & help with departing from your BPD r/s.
BUT what is most important about YOUR journey of learning is NOT about BPD but about YOU ... .and why you are the codependent / perfectionist / rescuer that you are as GooglyMoogly points out. On your journey you'll find no one here that will judge you. But this is YOUR journey to walk and along YOUR journey you will stumble ... .because we all have. Come talk to the group ... .someone will always be here for you. We won't tell you what to do or what choice to make ... .what we will do is pick you up, dust you off & pat you on the butt to get you started on your journey again. It's then you have to decide to sit back down & do nothing. Continue down the same path & see how that's going to continue to work for you OR choose a different path that doesn't lead you in a circle back to that same point ... .the choice IS and has ALWAYS been YOURS to make.
As GooglyMoogly points out ... .THIS IS NOT YOUR FAULT~! AND focus on YOUR life~! Learn to like yourself, Learn to Love yourself, learn that's it's ok to be alone and that YOUR happiness is NOT found by making OTHERS happy ... .as GM says, being a codependent you can work on yourself & change YOUR behavior because it's a learned behavior. It will most likely take a hard trip back to your childhood to see where you're behavior began ... .this is VERY hard & challenging BUT others including myself have done it. We've emerged from that journey a much better person having learned from our past in order to change our future.
You said,
"I need to work on me now and its hard. This is my third BPD relationship. How do I let this go?" YOU answered YOUR own question by making the statement first.
"I NEED TO WORK ON ME" As I said earlier this is NOT about your BPDr/s but this journey you seek is
ALL ABOUT YOU~! You already know that you have codependent behavior ... .that's a good place to start. Leave the BPDr/s alone ... .
As GM point out ... .get out & talk to people. Get out for a walk in the morning ... .heck a mile only takes about 15 minutes at a slow pace. Stay away from the junk food because NOTHING good comes from that ... .NOT EVEN YOUR POO

And yes that was suppose to be funny which brings me to the next thing ... .get YOUR sense of humor back. Go out to a comedy club with friends. Watch a funny movie ... .laughter is some of the best medicine. Make sure you're getting some good sleep ... .7-8 hrs is really needed not only to heal your body after a hard day but heal & let your mind rest after a day of dealing with life.
Take moments throughout your day & really ... .I mean REALLY enjoy the small things in life. I get up & watch the sunrise with a good cup of coffee. It's a simple thing to do but so relaxing ... .it renews my sense of self everyday & makes me realize that each day is short & needs to be explored & lived for me. Listen to nature on your walk ... .go to a park & listen to kids laughing. Take yourself out once a week for a movie & a bite to eat maybe ... .get a couple of friends & go explore something on a day trip in your local area that you've never seen before. BUT live YOUR life for YOU~!
Come back as often as you need to ... .more importantly as much as you want too. Read, learn, ask questions.
@GooglyMoogly "GM", You're new to the group too so welcome. You've given some good guidance from your experience ... .I look forward to seeing more from you in the future.
J