Talking To The People Who Once Picked On Me?

I use to weight 200 pounds I was unpopular at school, Not a day went by when i didn't hear the world "lard ***" My only friends were my group of 4 people who were my best friends. I now weigh 135 pounds, my before and after photos look like two completely different people, All of a sudden the guys who made my grade 9 life hell are inviting me places and wanting to sit by me, I don't feel right talking to these people, The only people I want to talk to are my group of 4 because i know they like me for me. Am i holding too big of a grudge against the bullies?