How to get help with my self harm?

I self harmed when I was a teenager cause of sexual abuse that was happening at the time. And to self harm just made it feel better but then I would hate myself for it. Fast forward a few years I’m an adult now with a 7 week old and I scratched up my leg cause I felt like I had no control over my own kid. And when I feel like a bad mommy that’s the first thing my mind goes to... idk if it’s postpartum depression or what but idk what to do.....