Thanks for all the great replies!
Yes, we both are seeking professional help. I'm not sure of what issues my wife is seeking to deal with, but she is seeing a counsellor and also talking to a poly friend who has been poly for a long time.
I'm seeking help about how to move on from the pain that I feel and be happy independent of whether my wife is able to open herself up to me or not (which is her answer to my questions to answer your question DH).
I don't think forgiveness is my issue in moving on from the pain. I can totally understand why she has the protective wall up. I can understand why she has been hurt. Acceptance may be closer to the truth. I am finding it hard to accept that she continues to keep the barrier up for such a long time. But also the fact that the barrier is there (even if it is understandable) but not there with someone else is painful to see. It is especially painful because it is in my face all the time and I am always confronted with it. Any more words of wisdom of how I can deal with the pain that is always in front of me??