How do i deal with an 18 year old student?

I am a new math teacher fresh out of college and my students are all well behaved except for this one. alex is an 18 year old senior and hes very rude. He gets all a's but he disrespects others and his choice of language is horrible. He curses like crazy, gets into a lot of fights, and last week he lifted my skirt,said "niceee" while his friend took a picture on his phone for him. I reported it to the principle but after he got in trouble he told me he didn't care. Which tells me he's still going to misbehave. I don't know how to deal with a bad student like him. I'm thinking it's something going on in his family but I'm unsure, what should I do?