Ashamed of who I used to be

Has anyone ever experienced this? When I was a teenager I used to be a complete pushover who'd always put others first even when it was a stupid idea or completely unnecessary. I made myself suffer for no reason and was a complete doormat. For years I suffered with issues involving my looks. I saw myself as this ugly, fat disgusting monster.

I just feel so ashamed of what I allowed people to say to me because I had no self esteem or dignity.

Has anyone else went through something similar?