The time I walked in on my sister masturbating

This is my throwaway account:

I (20M) rent an apartment and live alone. I’ve been working all through high school so I was able to save up money along with support from my parents to move out. Same case for my sister (20F) who has her own place. The rent isn’t too expensive, $950 a month and it’s small but spacey enough to live comfortably and have everything I need. Me and my sister have always been close (obviously because we’re siblings but I just felt like mentioning it) as well as love going out with our parents or just the two of us hanging out whether it’s shopping, gaming, going out to eat, chilling at each others apartments etc. We’re very comfortable around each other and aren’t afraid to get too descriptive or worry about coming off as annoying. After she split with her bf she knew since high school, she was feeling down lately. So of course I was very supportive of her and made sure I could keep her mood at ease anyway I can. One day when she came to visit me at my place over the weekend, I told her I was gonna go out and buy some snacks for us to eat like we always did. She was laying down on the couch in the living room when I left and was kinda drifting off to sleep. I went out to the dollar store which was like 20 minutes away because cheap=more snacks to buy. That day it was a bit packed so it took me some time to wait in line and checkout.(There was only one register open for some reason) I returned to my apartment with a bag full of snacks and placed it in the kitchen. Just a few feet past the countertop, I noticed she wasn’t on the couch. I assumed she took a quick nap and went to the bathroom after waking up, so I opened up a bag of chips and started eating. After a few minutes, I wondered what she was doing and thought she wasn’t here at first. She wasn’t in the bathroom so I went to go check my room. The door was closed which made me think she got up from the couch just to nap in my bed. I entered my room after opening the door and saw everything. She was pants down on her bed using a vibrator on herself while looking at her phone most likely watching porn. We both screamed and I looked away. She started cursing me out and I shouted at her to leave my room and wash her hands. I heard her stomp her way out of my room and I instantly pulled the bedsheet off and put it in the hamper I had in my room. I saw that my sister had left the bathroom and she stood in the living room continuing to bitch at me. I quickly went over to wash my hands. After that, I walked up to her and spoke angrily asking her why she was doing that on my bed. She told me that I should’ve knocked (which irritated me because I think it’s fucking stupid that I should knock before entering when I’m in my own apartment) I then yelled reminding her of whose place this is and she said “it doesn’t matter, you still should’ve knocked”. I told her that she shouldn’t have been doing that in the first place and she responded telling me the reason she did that was because of how stressed she’s felt lately due to her breakup which motivated her to “take a moment for herself”. I yelled telling her that her breakup has nothing to do with this and asked her why she didn’t just go home if she couldn’t resist the urges. Her reasoning was she didn’t want to just leave after I went out to buy snacks. I got even more fed up beyond that and just told her how she was being an impulsive retard who disrespected me along with my home. (who wouldn’t be pissed at that?) I then told her that she has no right to be angry and that if she really wanted a “moment for herself” in MY bedroom she shouldn’t have done it with the door unlocked. I even took another jab and suggested it’s almost like she wanted me to walk in on her. That set her off and she started yelling in my face. I just told her that I don’t give a fuck what she says because she’s wrong and yelled at her to leave. She seemed pretty sad but I didn’t care, at least not until after she left. What I was more worried about was the fact that I just saw my sister in a way that I’ve never seen her before because she lacked self-control in the moment. (My door is on the same side of the room as my bed so I had a very clear view and wish I could just unsee it) It’s been about a week since this happened and honestly, I don’t want to speak to her anytime soon since she tried to pin the blame on me.