What should I do?

I was with my ex for three years and 4 months before he slowly stopped showing up or replying (October 2nd was the last day I heard from him). I kept his number unblocked and he messaged me last month saying he was sorry and he wanted to get back together. I already had plans to move on and be happy while focusing on myself so I told him no. He has been trying ever since and I don’t know what to do because he was my best friend. I have had several bad/sad moments ever since and haven’t been able to address them. We snapchat every now and them and now he is saying that I am sending him mixed signals and how he feels like trash. Although I wish to tell him he is because he chose friends and hustling over me, I simply cannot because he is a genuine good person who would always put my needs first. I told him I just wanted closure because the decision he made one day to the next was unexpected. He says he was “stuck in the past” but won’t tell me in what way or how so. So I guess my dilemma is whether I block him without closure so he can also move on even though I don’t really want to. It’s more of a “I HAVE TO”