I guess this is simple "splitting". They see us as all bad or all good, no in-between, and seem to alternate between the two versions at will.
My BPDmom liked to either tell people how proud she was of me or tell them made-up stories about what an awful person I was. I could image some people must have thought that she had two sons
There's a classic BPD book titled "I hate you, don't leave me" that catches nicely this theme
Worth a read in any case.