My world is flipped

I feel so out of place, I just lost the love of my life and I've done everything I can to try and get him back, I begged him to try and understand what we had and that it won't be easy to find someone who will go through the things we did for each other.It's so hard because he keeps telling me to move on and that there's nothing more but he just rushed into a another relationship the night we got into a big argument and he didn't give himself time to think.I don't know what to do and I am feeling so many emotions that are so overwhelming. It's not like we were casually dating, we lived together, talked about the future together, we were established but now he's throwing it all away because he wants to talk to other people because he says we've tried too much and we just aren't working out. I can't let him go and I just keep digging myself into a bigger hole. I try to remind him of what we had but he told me he's just going to end up cutting all ties with me and blocking me if I don't try and move on too. I know he's going to realize that what we had was what he wanted and not some casual relationship but he's not seeing it and before it's too late he we won't be able to repair the damage because at the moment it is still repairable.I just really had to vent and need advice on what to do, I am afraid to let him go because if he just realizes what we had now, we can just go on and fix it.I just need any advice, I know to just leave him alone now but it's so painful and he was my best friend, I seen him every day for so long that it hurts so much for him not to be here, every day I just wish he'd come home.