He says he loves me but hides me, insults me, and won’t leave me alone. What is this?

I know this situation isn’t right, but I’m struggling with what to actually do, especially because we’re in the same university and the same class. This guy has been pursuing me for four months, saying he’s in love with me and sending sexual messages, but he only ever talks to me from a fake account and tells me to keep everything secret. He also texts another girl things like “good morning beautiful” and says she’s just a friend, even though the tone feels romantic. Recently he sat next to me in the cafeteria and started asking if I like watching porn, what the ideal penis size for a man should be, and even said, “Would my girlfriend get mad if I slept with another girl?” I felt extremely uncomfortable. When I questioned him before, he even called me “brainless.” On top of everything, he constantly sits next to me in class even though I’ve been trying to distance myself, which makes it harder to ignore him. Logically I see the red flags secrecy, flirting with someone else, sexual comments, insults, and not respecting space but emotionally I still feel attached. Because we’re in the same class, I don’t know how to walk away without making things awkward. Should I block him? Confront him? Just distance myself? How do I detach when I have to see him almost every day?