Welcome. I am sorry you are hurting. From the story my first impression is -- "More education then." Could start here.
And other places:
If you are after ethical, honest polyamory then you could learn to get comfortable with hard truthing. Speaking it, and hearing it. So maybe work on communication skills? Because if you can articulate your wants, needs, and limits clearly from the get go, there is less conflict later because people know what you are after. How are you listening skills? So you can hear their wants, needs and limits well?
Of course life is life. Nobody and nothing is perfect.
So thinking about your conflict resolution skills doesn't hurt either for the times when kerfuffles happen. It's not about a relationship avoiding all conflict ever. It's about HOW you navigate it as a team and pull through together.
I know that's all general advice.
But I want her back, in whatever way I can get her. I do love her and I am seeking professional help to get things fixed in my head, but I am at a loss for what to do next... Is there anything that can be done? Can I fix this? And how do I do it?
I really don't know if you can repair broken trust there. She's the only one what can answer the "Is she willing to work on it with you still or not?"
I hope you have made apology at least, even if she does not desire risking giving you a "make amends" opportunity. I hope she can forgive you so she doesn't carry bitterness around. But those are all separate components. It's not like when you say you "I am sorry" you are guaranteed "automatic forgiveness" and "automatic second chances." That's for the person who was trespassed upon to decide to grant -- depending on if they are still willing to go there or no longer willing to go there with you.
I'm glad you are going to counseling and trying to work on yourself to become a better you. That's always a good thing -- and something you can be proud of regardless of how this one particular relationship turns out.
So take a deep breath, and keep on keepin' on. You can do it!