Was this completely rude and inappropriate of him or what?

I have been seeing this guy for about a month or two. We have had a few times. He invited me over to a party at his house. I came over - it was just him and his guy friends. Which was totally fine with me. He was very charming and attentive the whole night. And then, around 2am, I noticed he started becoming very anxious and texting on his phone. I noticed him talking to one of his buddies, reading a text on his phone. He came over and said he needed to talk to me for a minute. He said there are some friends coming by in a few minutes. He said one of them is a girl that he has been dating. He said he realizes it is awkward with me there, he apologizes and that she will not stay long. I didn't really even know how to respond. And then he says she may not even show up. A few minutes later, the girl shows up. She seems like a total skank. She was wearing a very tight, short revealing dress and stripper-style stilleto heels. Anyway, he went to open the door for her, so I didn't see how they greeted each other. Then when she was there, he seemed very friendly with her, but he didn't kiss her (that I saw) or anything like that. He poured her a drink and she said she wasn't staying long. He didn't introduce us. He asked her to go outside onto the patio with him, where they talked for a few minutes. Then she came back in. His friend said he needed to go home right away and if she could give him a ride. She resisted at first, but then agreed to give him a ride home. So she left. She stayed about 10 minutes all together. It was very apparent that he and his buddy were very anxious to get her out of there. They both walked her out to her car, then he came back in. Anyway, I was pretty disgusted with the whole thing, He apologized and said he got rid of her as fast as he could. Then he said they are not sleeping together, just friends. Which I have a hard time believing. Why would a girl pop-in on a guy's night dressed like that at 2am? For coffee? Anyway, his friends left shortly afterwards. I had intended to stay the night, but after that I wasn't in the mood. I told him it was late and I feel like going home. He insisted I stay. So I did. Although I really didn't want to. And I probably should not have anyway. But I did. Anyway, I don't know what to make of the whole thing. But I think it was completely rude and inappropriate.