1) Are you sure they are haters they may genuinely look to your success as a model and want to emulate your success. Not in a hateful way but because they like you. If you really pick up on the "hate" vibe. All I can suggest is being civil but not too warm and open , answering questions without too much detail etc and finding reasons to leave the conversations. You can't be mean (small town girl myself I understand) but you can be less forthcoming on the deets.
2) I'm going against the grain on this. How do you feel about the guy, did you like him before? Were you friends. in a platonic way? Was he always kind at least? I don't know just things to consider if he was completely ambivalent to you before then I'm with everyone else but if there was a warmth and connection before but it just never went anywhere... there may be more to it than the weight loss?