I spanked my dog now I feel like shit. Help with how to train her?

So I’ve been having a rough two weeks. Just moved into my new home, with my puppy and cat. Safe to say it’s been hectic and stressful. Lol.

Well anyways today my dog bit my cat. I know she was playing around, but it terrified my cat. Without thinking I sparked her butt and yelled “no!!!” Not super hard. But it scared her :(

She got scared and ran into our bedroom. She is fine now. She’s all normal and licking me, after I held her and apologized for an hour. But I’m scared that she is going to be scared of me now :( I feel so horrible for this. I’ve never in my life spanked a pet. How can I train her to not bite without resorting to violence? I have to train her to not bite. She is going to be huge one day and if she bites someone she can very easily kill someone or seriously injure a person.. But I don’t want to spank her ever again. It doesn’t seem like positive reinforcement has been working. I keep giving her her toy when she bites but she continues biting everything. Ive never had a pet do it this bad and she gets really aggressive and growls and everything. I’ve tried everything and I’m just not sure what to do. Should I bring her to a professional trainer? Also will she forgive me for spanking her today? feel like shit and I know it’s just going to make her biting worse. Thanks