Welcome back ballerina802
My family member with BPD (not diagnosed just suggested by my psychologist after many stories and struggles) and I have reconnected a lot lately. I feel as if my guard is going down and I am about to jump back in emotionally. She has improved a lot after I started putting up boundaries and having less and less time between when we talked (used to be daily, moved to bi-weekly and now back to every 2-5 days).
You feel like her behavior has improved a lot after you started to set boundaries with her. Do you know if she has also been doing some work herself to try and deal with her issues? Do you feel like she acknowledges that there might be something wrong with her behavior?
I'm just feeling lost and insecure with it all. I miss the relationship we had but I'm scared to jump back in
How would you describe the relationship you had, also taking into account all the things you've learned about BPD? I think your fear is quite understandable given what you've been through with her. No matter what you decide to do, I think it's very good that you've had the support of a psychologist to help you process all of this and have also been able to set boundaries with her

When it comes to dealing with people with BPD, boundaries are essential to protect and preserve your own well-being. You might not be able to change the other person, but by changing your own behavior and setting boundaries, you can influence the dynamics of the relationship

I don't understand why she doesn't want me to be a part of her online life, even thought I know it's just "stupid facebook."
I can relate to your feelings about this matter. To you it's clearly not just "stupid facebook" because she deleted you from it after deciding not to come to your wedding. Could it perhaps be that now that you are reconnecting again, this block on facebook is a constant reminder of this painful memory? Do you feel like as long as she still blocks you there, you can't really reconnect with her like you used to?