I caught my friend who needed a visa, and I helped him get one, and he took a shit in our bathtub.

Throwaway account. I know I shouldn't be telling anyone about this, but it's too funny and horrible to stop thinking about it. The events took place a few days ago when one of my friends came from another country to study here. In exchange for his help with getting his visa, I planned a road trip for us. We were going to a city that is about 150 miles away. We were having a great time reminiscing old stories and stuff. It was already the second day and we had already visited almost every place we wanted to visit. At first he would stay in the hotel and I would go back home, but this time he told me that he wanted to stay over at my house because we were going to wake up early the next day and he would help me clean up and stuff. I said okay because I knew he wouldn't be able to pay the hotel by himself. We got home at around 12AM, we were tired and I went to sleep right away. At around 3AM I woke up to go to the bathroom, we were living alone in the house since my parents moved abroad because of work. When I turned on the light in the bathroom I saw him in the bathtub, turned away from me, and I thought that he was brushing his teeth. So I yelled at him telling him that I'm about to take a shower but he didn't answer and I just thought that he was deaf or something. It was only when I went closer to the sink that I noticed his posture. His pants were down to his knees and he was taking a shit in the tub. I slowly backed away because I didn't want to startle him. I closed the door slowly and I stayed in my room until morning. I didn't know what to do, I told some of my friends and they told me to get seriously pissed at him, others told me to write it off as a bad joke, but I knew that he's not that type of guy to play pratical jokes. I knew what to do when he came out. I told him in the calmest tone possible and with the straightest face I've ever had. "Yooo, what the fuck is wrong with you. You shit in my bathtub?" To my surprise, he was very calm and started to make excuses. He told me that he had to shit really bad and he was afraid to wake me up, and he didn't want to shit in the toilet because he was going to make too much noise. I let it slide because I really needed his help to get the visa, and I just told him to clean it up. He was surprised that I let it slide and he hugged me telling me that I'm his brother and that he knows that I've forgiven him. I didn't tell my friends about what happened because I didn't want them to think that I'm an idiot and I knew they would tell me to kick him out, but I didn't feel like it. I didn't feel any animosity toward him, I just felt a little weirded out about the whole thing. So I decided to write it off as a bad joke. I felt like I was going crazy because I couldn't stop thinking about it. I wrote it off and everything was fine. We continued our trip and I even let him stay for a few days at my house. I even gave him a ride to the airport so he could catch his flight home. I thought that I had forgotten about it until I was taking a bath and I remembered that the incident happened, and I just couldn't stop laughing. I know this is a long post but you guys have no idea how much it tortures me. I know that I'm not going to see him again unless he comes back to visit, but I feel bad because I let it slide. I don't know I might be feeling bad because I didn't punish him. The whole thing just makes me laugh, and I don't know what to do. The whole thing is driving me crazy. Should I let it slide and forget about it? How would I even bring it up?