I'm Jim. Welcome to the forum. Poly is not intended to be a lifestyle that makes someone feel bad about themselves or their relationship, in my view. My sympathies go out to you for feeling the way you do.
"Secondary" can be a misleading, and often misused term, I think. Some folks will use the term "Other Significant Other (OSO)." The key word in that term is "Significant." If you were treated as "Significant" rather than "Secondary" your story would be much more positive and uplifting. There's no requirement here to be positive, or uplifting, in terms of the forum. In your relationship, though, do you not have a right to be significant and therefore feel rewarded and cherished? It's always difficult to get a true picture of a relationship in an introduction, but my vote is that you clearly deserve better than what you're getting. It is very much achievable, and many poly people consider all of their partners to be valued equally. I wish you the best luck in attaining that quality of love.
I think you will find plenty of resources here to aid you in your relationship, or in learning to expect and even find a better one.