Hello Momsplit,
Welcome to the parent's forum - we are so glad you found us, though very sorry for the circumstances that brought you here. The first thing for you to know is that you are not alone in this difficult journey. Everyone here is walking or has walked a similar dark path and totally understands the place of intermingled love and excruciating emotional pain you are coming from.
If you are comfortable, can you tell us a little more about your situation? How old is your daughter and does she still live at home with you? You mention that you are also going through your own difficult time as well as dealing with your daughter's behaviours. Are you practicing self-care? As they often say on this board, it is vital that you put your own oxygen mask on first... .
If you haven't already done so, a good place to start on this site is perusing the tools and lessons on the right hand side of this page

Personally, I have found the resources and people on this board to be invaluable in helping me help my own BPD DD21 as well as myself. For me, it was a matter of realizing I wasn't alone and radical acceptance that allowed me to change my approach with my DD and move forward to a much better place than we were 9 months ago when I found this forum.
You have come to the right place for empathy and understanding, Momsplit. Please keep posting, it really does help. MomMae