My dad left porn playing on the computer

I just need to rant and see if anyone has any advice in dealing with this because I feel like I can't talk to my friends about it. I'm 19 years old and a junior in college but I still come home for the summer and holidays. Last night, I walked in the office in my parent's house and porn was playing on the computer. My dad was asleep and my mom is out of town so I know he was watching it. I know he watches a lot of porn - the office door is always locked when he's in there and I've come home and seen him slam the door shut while sitting at the computer, the history is always erased everyday. I also walked in on him watching porn when I was like 12 but pretended I didn't see it. I understand that most men watch porn and it hasn't really bothered me when boyfriends did but it has always made me uncomfortable knowing that my dad does everyday. Seeing multiple tabs left open last night and porn playing was so much worse than just knowing it's there. The history was also open and I saw where he searched for teen porn, pierced nipples, etc and I felt like throwing up. This morning I confronted him and he really tried to lie. I said "what the hell was on the computer last night, there were videos of people having sex playing" he said that there must of been a virus and he'll update the computer. He also said he's sorry I saw it and he doesn't want to see that stuff either. He's a recovering alcoholic and I'm sure he's also addicted to porn, he and my mom have a terrible relationship and don't even sleep in the same bed most nights. I struggle with depression and anxiety and have been hospitalized for an eating disorder multiplied times, I'm doing better now but I almost self harmed last night for the first time in 4 years. I don't even want to be in the same room as my dad, he's watching girls my age masturbate and fuck and I'm so uncomfortable. I feel like I shouldn't even brings friends over. If anyone has any advice for how to make myself deal with this, please let me know :(

Edit: thank you for the comments and support! Just wanted to respond to some people commenting that I should have "minded my business" and shouldn't have "interrogated him" - i didn't go sticking my nose in his business at all. I walked into the office to hang up a wet pool towel where my parents have asked me to (I teach swim lessons and have a lot of wet pool towels) and a video was open playing on the screen (the screen wasn't even minimized). And I didn't interrogate him, he came into my room this morning and asked me what was wrong (I'm sure he knew I saw it) and I said nothing but he kept asking and then I just blurted out what I explained above. When he said it was a virus, I didn't even say anything else I just said he should fix it then. I didn't interrogate or argue.

Also, when I said how to deal with it, I meant more how do I get the thoughts out of my head and move on - I know I can't do anything to change him and don't plan on speaking about it again.