Hi there Sadforher,
Welcome back. I joined this forum last summer, and it has been a godsend for me.
I just had to say, that when I read your post, I overwhelmingly heard FOG FOG FOG.

I'm going to challenge a couple of things, and I'm hoping that's ok

First off, I have to apologize to all of you.
Eh? Posting here is voluntary dear friend. It appears that perhaps you have been conditioned to apologise

for things
you don't need to apologise for. Does that fit?

It's ok, sadforher. We're here for you. It's support - without obligation!
I did not want to think about it anymore while I had some happiness and that was selfish and I'm so sorry.
Eh? Why was having a bit of happiness selfish? That sounds like your pwBPD talking again, because you were caring for
your needs instead of theirs. The good news is
that's not selfish...it's
responsible.

So good for you! The time is always right to care for your own needs.
Now I have finally found my mom an apt near me and am having anxiety over dealing with her moving and outbursts because she is scared to live alone.
She's pushing your buttons. This is the obligation and guilt in FOG, which is being driven by her fear. If you get sucked into this vortex all over again, you already know what will happen. Figure out what your boundaries are. Use your own values to help you with that. Then hold the boundaries you set. Yes she will push back, but stick to your boundaries anyways. Or you will get sucked into that black hole.
Have to been able to be in touch with your therapist again yet? I found the support of my T along with this forum to be super helpful. Do you live alone? Partner? Room-mates? People you trust?
Welcome back.