Old Ex Wants To Be "A Friend"

I've tried to stay on positive terms with my ex of 3 years ago. He saved my life during Hurricane Sandy in 2012 and I lived with him for 2 months until my apartment was redone, after which time I moved back to my apartment and my ex shut down on me shortly after - saying he couldn't help me anymore and he was tired of helping me rebuild.

Months after shutting down on me, he apologized and we tried hanging out, but I lost feeling for him.

Now, he's contacting me AGAIN and I told him I've just come out of a very long and intense relationship. He is still in love with me and wants to try to be "friends" and said if I need someone to talk to, I can call him, but I really feel like he's old news :(

I don't want to curse him out or tell him straight out leave me the hell alone...It's hard to tell him that the fact that he shut down on me and stopped talking to me after saving my life REALLY set the mood for how I look at him. Also, he's in his mid 50s and I'm in my 30s..I want to get married and have a family and he's not on that level anymore. He's said he wanted me to move in with him and should have NOT let me go back to my apartment.
So I feel like he's only talking to me because he feels guilty about what he did back then.

He keeps messaging me now and I tell him I'm not ready to talk to him and I don't think there's a future between us.
He really doesn't get it and I simply no longer answer him when he texts me.

I don't want to be mean to him, but how can I tell him he screwed up and I can never see him the same ever again?

I don't think he's feeling guilty. Rather, I think he's lonely and you seem like a good option.

How can you tell him that he screwed up and you'll never see him the same again? Well, I think you've come up with exactly the right words already. Use them on him.