Letting Go of the Past

Can a person ever let go of their past? To my friends I still feel like an outcast. I've made my fair share of mistakes that weren't smart. I've made amends for them, trying a new start. I gave everything up and went straight. After that I went to college and did graduate. I thought they would see the new man I've become, but they didn't, they still look and treat me like I'm dumb. It seems like anything that comes out of my mouth, any word, someone will chime in and say, that is the dumbest thing I've ever heard. I don't understand why I even try with them anymore. Probably because they are the only people with I have a rapport. I barely hear from them, they rarely call. Today I just have myself and feel so small. Most of them I used to call bro, but my past, they just won't let go.