Your post reads like a vent to me. I hope you feel at least a tiny bit better. BREATHE. BREATHE. You sound all pent up.
Why does monogamous marriage make you feel "caged in?" What do you want rather than being "caged in?"
Since you had a triad before and that went well -- what is the jealousy thing stemming from?
- The general dating process?
- Or stemming from your partner becoming sexual with new people faster than you are comfortable?
- Or something else?
What needs were met in the triad that are not met right now that you DO want met?
Why do you think that poly = slut? Who is making you out to be a slut? Why does what other people think bother you? What kinds of people are around you that do this poly slut shaming thing? What kinds of people would you rather be around?
Could think about articulating it from the angle of what you DO want. Rather than this big list of stuff you DO NOT want. Could try focusing on what you DO want instead.
I could tell you I want OJ to drink. Or I could spend all day telling you I do not want milk, I do not want coffee, I do not want vodka... and you still would not be able to help me find what I DO want. Because you do not know that I'm after some OJ.
So... perhaps if you articulate what it is you DO want, others on the forum could help you find it for yourself better?