Sounds like a hard situation. Frankly I think it's selfish (albeit honest) of him to say "hey, we HAD a romantic r/s, and I don't want that anymore but I DO want you to stick around as a friend". I know very few people who would be comfortable and able to do that.
Again, it is good he was honest with you. But you are under NO obligation to remain friends, particularly since you have stronger feelings than that.