Did I do the right thing?

Me and my mom were grocery shopping and when we were walking out if the store this I'm assuming boyfriend and girlfriend were arguing. The girlfriend had what I'm pretty sure was a coffee and through it in his face and he screamed. My mom grabbed me and told me to keep walking but she started hitting him and I told my mom I think we should call the police. But my mom told me to mind my own business. This dudes on the ground now and she kicks him in the face to I snatch my hand from my mom and dial 911. I think the girl saw me staring so she yelled at me asking who I was calling and called me a bitch. I explained to the 911 operator whats going on and the girls goes up to me threatening to beat my ass and called me a hoe. I pulled out my mace and held it up and told her to stay away from me. She starts running up on me again and said "Bitch I wish you would". So I maced her. She fell to the ground yelling. I waited for the cops to get there and this bitch lies. She said her boyfriend had grabbed her hair and slammed her to the ground so she kicked him the face. And then said I had ran up to her yelling at her and then maced her. Her boyfriend was staying really quiet and she was yelling at him saying "Tell them! She ran up on me didn't she! Fucking tell them!" This kid honestly didn't look older than 20 and he was just hugging himself staying quiet so a cop took him alone to talk to him. They ended up arresting her. My mom started yelling at me for getting involved and telling me thats there relationship to work out. I'm like "Thats an abusing as relationship" and she goes "Well its on him for staying in it. Can't blame anyone but himself ". I'm hoping I did the right thing getting involved even though I had to mace her.