Hi, I'm sorry to hear you have bpd, from what I understand it's very challenging to live with and wanting to ctb is an oscillating feature of the condition? I think there are some people on here who suffer tremendously who would be better placed to advise, hopefully they might come forward for you.
As for methods and things, if you read through the various megathreads on different ways I think they offer quite a comprehensive idea of what's involved with each method which might help you make a decision as to what might be right for you.
Sending you a hug as I think it's not always a bad idea