Need help moving on - seeking guidance, please

Assalamu alaikum. I was involved with someone for about a year. At the start things seemed okay, but after four months his communication became all over the place - some days long calls, other days total silence. When I asked for more steadiness, he said his life doesn’t revolve around anyone and that this is just how he is. I later discovered he was still active on dating apps while talking to me, and he even said he was “looking for someone” while claiming he wanted something meaningful. I often felt like an option rather than a priority. He’d saved my number under a random four-digit code instead of my name. He said he does that for everyone, but after months of talking it didn’t feel right. I planned a thoughtful birthday surprise that took time, effort, and money. He repeatedly said he doesn’t like surprises and seemed annoyed instead of grateful. When I got emotional, I felt dismissed rather than comforted. Over time arguments turned into name-calling. I was called “immature,” a “know-it-all,” and “crazy.” When I explained how things hurt me, I was told I was overthinking or self-sabotaging. After all this, he’s asking for another chance. I had strong feelings for him and it’s hard to let go. Part of me wants to believe things could change, and part of me is just exhausted. Long story short: when I cared deeply, after wasting so much time, he’d call us incompatible yet still keep me around. Even now I replay conversations, question myself, and feel emotionally attached despite knowing this wasn’t healthy. He’s been toxic to me - when I tried to fix things he told me to move on and find someone else if I’m not happy. How do I detach emotionally and move forward without it affecting me? What helped others stop ruminating? I miss him so much - sometimes it feels like I’m addicted to being neglected, and I hate that I can’t move on. Please help me. There were times he was kind during outings, which makes letting go harder. I know the logical answer is to leave, but my heart and mind are at war. How do I break this cycle and stop obsessing over the “why” (why he behaves this way, why he’s attracted to other women) and start focusing on my own “what now”? JazakAllah khair for any advice or dua.