The thing of it is, if you are uncomfortable with the fact that there still seems to be some type of connection between you two, severing all forms of communication is useless. You need to be able to say to him, on the phone or in a letter, that you don't want to have any more contact with him. Otherwise, this same problem could present itself in 8 more years. Ignoring the problem (by not taking his calls and throwing away the letters) won't make it go away. It would be a whole new different story if you didn't still harbor some type of feelings for him, which it sounds like you do, even if only a little. I think that you need to know that you are able to say to him, and mean it, "I don't want to have these type of conversations with you anymore."
I agree, you should continue to pray on the situation. Get still until you feel as though God is commanding you to move. Don't make a decision, and then pray on that decision, that would be too late. Pray for guidance. I'm praying for you, too.

I know you'll be fine, you know what you want, just not exactly how to get there.