I used to have a similar relationship with my ex-husband. Both of us have mental health issues and both struggled with substance abuse while we were married.
Both of us exhibited unhealthy levels of jealousy and attachment. I grew to resent him for everything, but yet I didn't want him to leave me.
One day I had a realization and it was like finally getting up the nerve to rip off a bandade after having been afraid that doing so would hurt.
Now I can't imagine what I ever saw in him. Now that I am sober and having my mental health issues addressed and he is still in that same life rut, he seems incredibly pityful and unappealing. but I can clearly remember feeling like that I would simply lay down and die without him. Believe me, it passes.
You are not alone in what you are going through, unhealthy levels of attachment and unstable interpersonal relationships are part of BPD, much to my dismay.