lovenature, I'm so sorry you're struggling. Know that you're not alone.
The end of a BPD relationship is devastating, and often does leave us questioning and second-guessing everything we thought we knew.
It's up to us to filter through and find the legitimate questions and concerns -- obviously we need to change some things if we want to grow and open ourselves up to healthy relationships -- while not beating ourselves up, or becoming bitter, or ruminating/obsessing about things we can't control. It's not easy or quick work.
I too second guess. I know now I go more to the negative then ever before. I use to be a positive upbeat person but I feel very worn down.
I struggle with this worn-down feeling, too. I've been getting better with the negativistic thinking, but it was rough for a while.
Honestly, I think it just takes time, patience, and work. We've been hurt. We're only human; we're allowed to feel tired, sad, wary, selfish, angry, etc. It's unhealthy to
stay there, for sure. But it doesn't help matters to beat ourselves up for feeling these things.