It's really hard for me to discard anyone I really care about, whether it's online or IRL. Whether they messed up or they didn't. I have a pretty forgiving nature.
I feel like it's easier for people to let me go than it is for me to let them go. I'm still struggling with missing an online friend really badly, but I think it will be a cold day in hell before that person gives me a second chance, and gets to know the sober me. It's a real shame and it hurts me to the core. and as I told you privately I'm mad at myself that I can't just stop caring about this person, even with the relazation that I was likely never cared about by them.
So you're not alone, and you're not nuts in my opinion. Us BPD's (at least some of us anyway) feel and care for others very deeply.