If he's looking at (and possibly thinking about) other women then I (personally) would consider that cheating. Especially that number of people is kinda scummy. I think you'd be better off cutting ties. I've been in the same situation where the person I was dating and their friends were the only friends I had. And after we broke up I had not a single friend. But even though I'm not a very social person I quickly got new friends. It's been about 2-3 years since then and let me say that the friends I gained are more like family to me than anybody else in the world, and I'd take a bullet for any one of them.
Point is, even if breaking things off would mean you have no friends, that isn't a reason to keep a possibly toxic person in your life, especially if you think you're just going to be jealous of any of his new relationships.
But I don't know everything, I'm 21 just like you. All I can do is tell you my opinion and talk to you if you need it ☺️
Nobody can tell you what to do in life, so just follow your gut feeling.