This is your health that we're talking about! Although you can't control what he does with anyone else you have the right to say that unless he wears a condom with her that he won't be having sex with you. This is one of those things that you really shouldn't give up control on. I would also go and get tested ASAP to make sure he hasn't passed anything on to you.
Everything will be ok in the end. If it's not ok it's not the end.