My partner says mean and hurtful things to me to provoke fights

When I met my partner, he was poly and I was monogamous. When I started to explore more into polyamory myself, he expressed jealousy over the person I went out with and said he wanted to become monogamous with me. After ending it with his other partners, we were exclusive for several months before recently discussing opening things back up. I suggested that we reopen it because it was obvious he still loved at least one of his previous partners very much, but he always said he wanted to remain monogamous. He told me he wanted to get back together with his previous partners, which I was fine with, but then he went on a rant where he compared my influence on his life to my mom's influences on my dad's which was far from healthy and told me he loved his previous two partners more than me. When I told him those comments were unnecessary and hurtful, especially when he knows how I feel about my parents relationship, he said he didn't fully understand their relationship, but agreed that the comment on loving his previous partners more than me was not needed, though he thought at the time I needed to hear that because he expected me to fight back and then admitted that he had considered just cutting me out of his life completely at the time. Now every time he says he loves me it feels like a pit in my stomach and it makes me want to cry. I'm at a loss of where to go from here because I love him very much and I wonder if part of this is just New Relationship Energy taking over for him right now with the reintroduction of two former partners plus the added excitement of two new ones, or if he genuinely doesn't care for me that much.

This letter was originally about twice as long, and I edited it down for length, but what got cut was just a few more examples of your partner being cruel.

LEAVE THIS RELATIONSHIP. This is a person who attempts to pick fights with you just to trigger some conflict, who intentionally brings up and uses against you things that are sensitive points in your life, who threatens you with being cut out of his life, who explicitly says that he loves his other partners more than you.

NONE OF THIS IS OKAY and it borders on abusive. This is NOT excusable as “just New Relationship Energy.” NRE makes you do things like text your new partner all the time or have less time for your long-term partners for a brief period. NRE does not make someone use lies, accusations, insults, and threats to make your existing partner “want to cry.” This person is being cruel and unfair to you. “Love” is not enough here. LEAVE. THIS. RELATIONSHIP.