The contributions so far seem to be suggesting essentially that the ENTP should continue doing pretty much as he damm well likes, and bronte is just going to have to change her way of dealing with it. The only snag here, guys, is that it is a lot easier to alter one's outward behaviour (i.e. maybe learn some better manners) than completely restructure one's personality and type orientation, which is what a Fi dominant type like bronte would probably need to do were she to take this as lightly as you suggest and simply return like for like. It would take a very confident INFP with good extraversion skills to do this, and even then she would be vulnerable to being caught off guard and distracted and pressurised by having to deal with it at a moment's notice.
Even if she was able to deal with this sort of treatment in the way you suggest, and do so effectively, it would be natural enough for him to think that she actually enjoys playing his game (I think she has already made clear that she did not) which is only likely to encourage him to play it more, which would simply up the stakes and the pressure on her. There is also the problem that dominant Fi types do not like to upset or offend other people and are quite likely to actually be more hurt themselves and remember it for longer than the person on the recieving end should they inadvertantly (or with Fi self-critical hindsight even intentionally) press the wrong button. And I am sorry to say this, but NT types can be upset by barbed comments too. It's just that they don't tend to worry so much about upstting other people.
However, bronte, I wonder what your part in this is. I don't get the impression of you being very pro-active about it so far (though I could be wrong). Did you actually SAY anything to him about it. Directly? If you are seething or hurting inside but don't let anything show he is not likely to work it out for himself. If you want anything to change I really do think the best option is to be straightforward and direct with him and tell him what the problem is and when it is occuring, and that although you like him as a person you feel uncomfortable being around him when he says and does X, Y, and Z. If he really does like you and respect you I would hope he can be mature enough to at least try to work on his behaviour. If he's just looking for someone to bully and act as a passive target for his remarks, however, you might want to be a little more judgemental than is your wont as an INFP and consider that you are entitled to respect yourself, and are not obliged to be nice to anyone who is not prepared to give you it.
One other point: INFP's because of their reserve and definiteness about their own opinions can come across as somewhat inscrutable, and a little superior to others, even when they are not intending to be anything of the sort. You might want to consider that the derogatory comments could be a sort of subconscsious compensation if he is feeling intimidated by you. But I still think you have the right to expect a certain standard of respect.