Glad to hear you're doing better, ray.
While I'm not especially old, I have certainly put myself through enough bullshit in relationships to recognize it now. But you know what? It took a long fucking time to be able to not only see it, but call people on it and be strong enough to stand alone if that's what was needed.
So try not to get down on yourself for not seeing it while you were in the midst of it. Or, seeing it but choosing to ignore it. I'm sure there isn't s single person here that hasn't pulled the same trick on themselves.
You were in a vulnerable spot, needed someone, and to some extent, O filled that. The fact that the relationship ended shows how you've grown; you weren't content to sit and wait for the scraps that they were offering like a good little secondary. You wanted to be treated like a person and they couldn't give that.
What I'm trying to say is use this relationship as a learning experience. Figure out the good parts, and use them as benchmarks against future relationships. More importantly, look at the bad parts and watch for those traits in new relationships.