I suppose the good thing is that you realise how seriously unhealthy this relationship is - and not just for you but for him too. You each deserve a life outside of each other and i'm afraid relationships only really survive if both members can reconcile themselves to that fact. I think professional help would be of tremendous help to you, perhaps even couples therapy as well if your partner is up to it. Outside of that, i would try and take smaller steps towards bettering your individual life. Do you think you could start by doing more things by yourself? What about joining some groups that interest you and begin to broaden your social circle? I realise that any kind of friendship or relationship can be tough when you have BPD but even if you're just making more of an effort to connect to the wider world - that's a good beginning. Eventually you might find that you actually quite like a degree of independence, you can make decisions for yourself based on what you want. In the right frame of mind that can feel empowering instead of daunting. But the decision has to be made by and for you - if you don't truly want to break this cycle there's not much anyone else can do. Keep posting, we'd be happy to listen and help in any way we can.