Glad to hear from you again, Tinyblu. I was wondering what was going on with you.
I'm truly delighted that you have finally broken things off with this guy.
But don't beat yourself up over it. Think of it as 6 months of great sex, not as a 6-month mistake.
Also, I don't think you were dumb. Right from the beginning, you were worried something was wrong. At one point, you said something like you thought you might be the dumb one or the dumb pussy in the equation--which shows that you really weren't, because you suspected the truth. You just didn't want to believe it because you had all sort of feelings--which happens all the time.
So your instincts always were smart--which is why you were posting here to begin with, and why you were saying things that caused everyone here to advise you to dump the guy. We were trying to tell you to listen to your instincts, that's all.
I think experimenting and taking emotional risks is better, in the long run, than being too afraid to try new experiences.
A suggestion: it sounds like you're drawn to men who are super-sexual and dominant in bed. That's cool (so am I). But men can be dominant in bed without being self-centered, manipulative assholes. (In fact, they're much better in bed when they are not self-centered, manipulative assholes).
So you might want to do some self-reflection and become comfortable and open with what you want sexually. It's common to confuse sexual dominance with general asshole-ishness, and to become attracted to asshole-ishness by accident, when it's really just the dominance you want but you don't know how to admit it.
Other thoughts: my sympathies are with you on losing the woman you were close with as well. That's probably the aspect of the situation that non-poly people won't understand--your pain over losing her friendship.
I had a similar experience with my college boyfriend (and he wasn't even dominant in bed!
). I felt close to his primary partner (she and I weren't sexually involved, but I considered her a good friend and really admired her). She started acting crazier and crazier, more and more manipulative, doing things to sabotage my relationship with him, etc. It took me a while to catch on. And even longer to admit that my boyfriend was contributing to the situation (if not causing it outright).
Anyway, I felt really betrayed by her, and so fucking angry I could hardly think straight. It was years before I could admit to myself that at one point, I had really admired her, and that it hurt so much to feel that her friendship with me had been false to begin with because I still missed her friendship. That's something I could never talk about with most people--they would just say, "But she was so crazy!"
So I'm sorry for that. Let yourself grieve, and eventually you'll glad that these people are out of your life.
In your situation, I think the guy was thriving on getting women to fall for him and fight over him. Yuck yuck yuck. Polyamory is fine, but that's not at all what that was.
The thing that bugged me most about him--you said that he told you he would basically drop you if you saw other guys. That means it wasn't "poly-fuckery" either--where everyone has a lot of sex with everyone else and no one cares about much of anything. It was about controlling you and making a harem of women who were all helplessly devoted to him.
Here's an example of how it could have been worse: a friend of mine got involved with a guy who was involved with many women. She was open-minded, not looking for anything serious, and excited to be trying a new "type" of guy. But soon it became clear that the guy was deliberately creating jealousy and encouraging craziness in these women.
My friend ended up having her phone account hacked by one of his other women, who sent harassing text messages to his primary woman and made it seem like my friend had sent them. My friend was nearly arrested for harassment, which could have cost her her job.
My friend is an intelligent, happy, emotionally stable woman, and she was totally thrown by this.
So take the sexual experience, Tinyblu, and don't dwell on the rest. Good luck!