Pete raped that woman and it was not "ambiguous".
It was no more ambiguous than when Greg raped Joan.
The following article explains this in more depth, in case you are sitting on the fence about that particular story point:
Pete Campbell Is A Rapist
Why is it even a question? She very obviously didn't want to have sex with him! I don't care how much you like Pete (and I like him!) he's not getting let off the hook here. Let's call a spade a spade and a rape a rape. Let's admit that ordinary men rape women all the time. Every day. If you haven't been raped by one, you likely know someone who has. It doesn't mean that men suck or that men can't change, but when we start talking about ambiguity in pretty clear cut cases of rape (I'm looking at you, Hollywood), we're not putting the responsibility where it needs to be: on the shoulders of men who distinguish between rape and "coercion".