Should I date a friends ex?

There’s a guy I really like in school called Will, only trouble is, he is the ex of 2 years of someone I know. I wouldn’t say she is a friend because to be brutally honest she annoys me but we have the same friends, so i’m not sure what to do. Obviously I’m not going to do anything yet because I don’t know how he feels, but if he does like me I want to know how to go about the situation. We always have a laugh together, sounds wierd but we have like our own language almost. My friends seem to get annoyed by him and they all rub each other up the wrong way, but with me its not like that. He’s told me before that i’m always the nice one that is never horrible or bitchy (unlike his ex). We had to do dancing lessons for a christmas dinner (kind of like a mini prom type thing) and we were randomly put together. It was soo much fun and we work really well together. Thing is, I do really like him and think maybe he could like me but I don’t want to do the wrong thing by his ex. They broke up about a month ago, he’s totally over her and she says they’re just mates now. What do I do?