Is it smart for me to be trying poly/non monogamy right now? And is my partner being manipulative?

I started dating someone a year-ish ago. We’ve been non-monogamous the whole time but it makes me very uncomfortable.

Almost every partner I’ve had has lied to me or cheated on me. Its had a really powerful impact on me. I also tried poly/open once before and got hurt when my partner, who had previously told me they would never be monogamous, left me…. For a long distance, monogamous relationship. Still upset about that one.

In turn, it has made being in this relationship EXCRUCIATING. I care about my partner and I want to hang in there, but I have no fucking clue how to do it without losing my mind. I can’t just “not be jealous” or “practice compersion” because the roiling, visceral reaction I’m having whenever I find out that my partner is gonna sleep with someone.

How can I combat this and get past these feelings? REALLY LOOKING to hear from someone with a very similar experience.

And one another note…

We talked about boundaries and i mentioned id wanna know if they were going on a date or whatever. They added that they dont want “blow by blow updates”, which i later found out to mean “i dont want to have to tell you every time im gonna see someone”.

Am I over reacting, or is this totally ridiculous? It just seems manipulative to me. How can I trust them to be honest if theyre basically saying “ok i have to tell you when i see someone… but i dont always have to tell you, and that call is up to me, which means if I cross a boundary I can just not tell you and hope you dont find out”. My partner has already lied to me once before and I’m just unsure if I can even trust them to tell me if they cross a boundary.

I’m just sinking into this feeling that i just shouldnt put much effort into this relationship because im eventually going to be replaced.

Any advice?