I got into a fight with my aunt....Did I do the right thing?

My aunt came to visit me and grandma with her youngest daughter who is 6 and she did something bad so my aunt got mad n locked her in a bathroom she didn't turn the lights on she left her there in the dark crying like crazy and of course the girl couldn't turn the lights on since you can only turn them on or off from outside I was shocked but I didn't say anything at first but after 15 minutes of hearing a little kid crying i opened the door and let the poor girl out without my aunts permission I couldn't take it Anymore i mean if my aunt at least let the lights on I wouldn't have opened the door! But that's not acceptable she might beome scared of the dark forever or get nightmares Bc of this !!! When I was 7 i was sleeping in my sisters room then she left the house and locked her rooms door before she left she didn't notice me sleeping there I woke up in a dark room it was so dark and what was scarier that it was night I Couldn't see a thing and I couldn't even turn the lights on I was so small I was crying there for hours after that incident i have been sleeping with either grandma or my older sisters I had lots of nightmares I was able to sleep alone again at the age 11.