Advice on potentially blocking an ex?

So first of all I am fully aware that this problem is between me and my ex, I'm just asking for y'all opinions.So a bit of background my ex bf and I broke up almost 6 weeks ago due to the distance and him still being in love with his ex. I still love him and he still loves me, our feelings haven't changed at all.Obviously it's unhealthy and it's making us both sad. I have attempted to block him a few times all ending in him pleading with me not to block him, I know it would be best for me to. I feel like our feelings are too strong for us to just be friends and we can't be together so by that logic we can't speak at all right?Also I'm super worried about him getting another boyfriend, I obviously don't expect him to wait while I move on, but I'm not ready to see him move on. This is my biggest reason to block him, but for reasons mentioned I can't. I have a history of self harm and I am 90% sure if I see him move on while I'm feeling like this I will end up self harming.Any ideas on what to say to persuade him to get on board with the blocking?(It's easy to say "just block him" but it's a lot more complicated than that)