I am sorry for all that are struggling with right now. The mixed emotions seem to come with grieving the loss of the relationship and what I believe is healthy self-inquiry regarding your own views of relationships, who you are/were in the relationship, and your own limits and boundaries.
That being alone with peace of mind is better than going through what I have. I know that I will feel bad at times and it's along road but I will work on myself to get through this terrible experience learn from it and who knows what around the corner.
Like I said I may have bad days and feel how could this happen to me but I know it's a process I must go through to get to the other side. If I can get through my diagnosis of having HIV and live my life then I can get through this and at the moment I think I can do it.
It sounds like you have a healthy attitude toward wanting to recover from this difficult relationship and break-up.

Have you had a chance to read the articles on relationship break-ups when BPD is involved:
https://bpdfamily.com/portfolio-broken