Even if he was hurt, he shouldn't have blocked you, in my opinion. It shows bad communication skills on his part and a lack of maturity, in my honest opinion, since you did have a meaningful relationship with him, even if it was an "open" one.

I've had an open kind of dating relationship (and friendship) with this one guy who is keeping me in the dark. I texted him asking how he is doing, and he has not answered me. I have no clue what is going on: whether he is just busy or no longer wants to speak with me. He might just need space based on his crazy life, but it sucks, because the least he can do is explain his feelings. It really hurts. Even though my situation might vary a little, I totally know that feeling and empathize with you greatly and relate to aspects. It's hurtful to be ghosted.

Sometimes when people are mad, hurt, or going through something, they are simply not ready to talk. I think email is a good idea. However, I can't help but have a feeling he might unblock you when he works through some of these feelings of hurt, and he will be in touch, but it could take time. This is what happens often, although of course I do not know him or can tell for sure. Please hang in there, please don't be hard on yourself. You deserve happiness. Take care of yourself during this difficult time.