It does take guts to come here and admit publicly that you are feeling afraid and concerned. And yes responses can sometimes come across as hurtful, antagonistic or patronizing. Posting about your feelings in a public forum is definitely opening a door to the possibility that people won't be kind.
All of that being said, everyone's poly mileage may vary. If you like what you read acknowledge it. If you dislike it then disregard it. If you're feeling triggered or lit up then maybe its worthwhile investigating why you're feeling that way. Might be you're responding to something in the way it was written rather than the content.
Jealousy sucks. The core insecurities that it brings forward suck. It is a reminder that we are imperfect and need work. It means we have to stop and ask for reassurance. I was reminded yesterday in a post I put up elsewhere here that yeah, I do need to keep the focus on myself. This whole jealousy, fear, anxiety thing is an inside job.
The specifics of the original question are hard to comprehend for me as I would not have chosen to stay in this sort of situation. So I'm not going to comment on that (stay away from the negative feedbacK).
I will say that asking for reassurance by simply admitting you're afraid can help. Not asking for anything beyond just hey i'm afraid could you please spend some time doing (fill in the blank that helps you feel better. I'm not talking about processing feelings either, actual physical reassurance/ touch.) I hope your pain eases and you can find some relief from your insecurity.
The world was made round so we cannot see too far ahead