I really see a lot more growth in you because of this experience than I think your post is highlighting:
" I was advised by someone I used to be close with"= perhaps a lil realization that this person you USED to be close with was not the right one to take advise from? Hey, I'm 52, I can't even count how many friends have given me advise that just didn't work out well. It's hard to weed through who gives good advise, and realizing who doesn't is just as important.
"I gathered up the courage to ask her"= YEAH YOU! You did something scary that you felt would help you work on your recovery. I have learned to face a lot of fears, sometimes it results in physical pain, sometimes emotional. The important thing is that we no longer run away from it.
"I guess that's something I should have talked to her about from the very start"=Hindsight is a valuable tool in how you can approach this moving forward. When we know better, we do better. No one gave you a book or warnings beforehand, you did what felt right.
You were not willing to go no contact with your mother as suggested=Following the take what you need, leave the rest mantra. You felt the need to stay in contact with your Mom right now, and you were following your gut on that front. Our gut feelings can be wrong, but we must learn to start trusting those feelings again because only we as individuals have a better understanding of what may work for us and what won't better than anyone else can.
"Once I realized I needed to get out of my rut"= AWESOME!! This self awareness is crucial for our recovery. Sometimes we need to just backoff and let the emotions move through us, but where we have the most trouble often is not being able to recognize when we need to move forward and not get stuck in that rut indefinitely.
"I sobbed for the first hour or so, and now I'm starting to just feel anger."= This is my personal favorite because it sounds like you are actually working through the emotions instead of denying them or holding them in. You go girl!
Big hugs your way! Do not allow any of it to deter you from Al-Anon altogether. Accept it for what it is, a sponsor who wasn't right for you. The sponsor is not Al-anon, just another human being who has faults and needs and working the program in a way that works for her. Never forget it is a take what YOU need and leave the rest. You may decide you never want or need a sponsor in the future, that's ok. Let go, let HP approach, time will bring you more answers on what you need or don't need in terms of a sponsor.